diff --git a/lib/tsc.js b/lib/tsc.js
index dd19b4a1986..732778a081f 100644
--- a/lib/tsc.js
+++ b/lib/tsc.js
@@ -4787,6 +4787,7 @@ var ts;
         The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access: diag(2779, ts.DiagnosticCategory.Error, "The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access_2779", "The left-hand side of an assignment expression may not be an optional property access."),
         The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access: diag(2780, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access_2780", "The left-hand side of a 'for...in' statement may not be an optional property access."),
         The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access: diag(2781, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access_2781", "The left-hand side of a 'for...of' statement may not be an optional property access."),
+        _0_needs_an_explicit_type_annotation: diag(2782, ts.DiagnosticCategory.Message, "_0_needs_an_explicit_type_annotation_2782", "'{0}' needs an explicit type annotation."),
         Import_declaration_0_is_using_private_name_1: diag(4000, ts.DiagnosticCategory.Error, "Import_declaration_0_is_using_private_name_1_4000", "Import declaration '{0}' is using private name '{1}'."),
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: diag(4002, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_class_has_or_is_using_private_name_1_4002", "Type parameter '{0}' of exported class has or is using private name '{1}'."),
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: diag(4004, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1_4004", "Type parameter '{0}' of exported interface has or is using private name '{1}'."),
@@ -10941,6 +10942,10 @@ var ts;
         return !!node && !!(node.flags & 33554432);
     }
     ts.isInJsonFile = isInJsonFile;
+    function isSourceFileNotJson(file) {
+        return !isJsonSourceFile(file);
+    }
+    ts.isSourceFileNotJson = isSourceFileNotJson;
     function isInJSDoc(node) {
         return !!node && !!(node.flags & 4194304);
     }
@@ -17787,6 +17792,9 @@ var ts;
             propertyAccess.name = parseRightSideOfDot(true, true);
             if (questionDotToken || expression.flags & 32) {
                 propertyAccess.flags |= 32;
+                if (ts.isPrivateIdentifier(propertyAccess.name)) {
+                    parseErrorAtRange(propertyAccess.name, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
+                }
             }
             return finishNode(propertyAccess);
         }
@@ -25607,7 +25615,7 @@ var ts;
             typeLiteralSymbol.members.set(symbol.escapedName, symbol);
         }
         function bindObjectLiteralExpression(node) {
-            if (inStrictMode) {
+            if (inStrictMode && !ts.isAssignmentTarget(node)) {
                 var seen = ts.createUnderscoreEscapedMap();
                 for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
                     var prop = _a[_i];
@@ -31074,6 +31082,9 @@ var ts;
                 return ts.createIndexSignature(undefined, indexInfo.isReadonly ? [ts.createToken(138)] : undefined, [indexingParameter], typeNode);
             }
             function signatureToSignatureDeclarationHelper(signature, kind, context) {
+                var suppressAny = context.flags & 256;
+                if (suppressAny)
+                    context.flags &= ~256;
                 var typeParameters;
                 var typeArguments;
                 if (context.flags & 32 && signature.target && signature.mapper && signature.target.typeParameters) {
@@ -31101,15 +31112,12 @@ var ts;
                 }
                 else {
                     var returnType = getReturnTypeOfSignature(signature);
-                    returnTypeNode = returnType && typeToTypeNodeHelper(returnType, context);
-                }
-                if (context.flags & 256) {
-                    if (returnTypeNode && returnTypeNode.kind === 125) {
-                        returnTypeNode = undefined;
+                    if (returnType && !(suppressAny && isTypeAny(returnType))) {
+                        returnTypeNode = typeToTypeNodeHelper(returnType, context);
+                    }
+                    else if (!suppressAny) {
+                        returnTypeNode = ts.createKeywordTypeNode(125);
                     }
-                }
-                else if (!returnTypeNode) {
-                    returnTypeNode = ts.createKeywordTypeNode(125);
                 }
                 context.approximateLength += 3;
                 return ts.createSignatureDeclaration(kind, typeParameters, parameters, returnTypeNode, typeArguments);
@@ -38948,7 +38956,8 @@ var ts;
             return false;
         }
         function isEmptyResolvedType(t) {
-            return t.properties.length === 0 &&
+            return t !== anyFunctionType &&
+                t.properties.length === 0 &&
                 t.callSignatures.length === 0 &&
                 t.constructSignatures.length === 0 &&
                 !t.stringIndexInfo &&
@@ -42779,7 +42788,7 @@ var ts;
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }
@@ -43390,10 +43399,12 @@ var ts;
                 return type;
             }
             function narrowTypeByOptionalChainContainment(type, operator, value, assumeTrue) {
-                var effectiveTrue = operator === 34 || operator === 36 ? assumeTrue : !assumeTrue;
-                var doubleEquals = operator === 34 || operator === 35;
-                var valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? 262144 : 65536));
-                return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, 2097152) : type;
+                var equalsOperator = operator === 34 || operator === 36;
+                var nullableFlags = operator === 34 || operator === 35 ? 98304 : 32768;
+                var valueType = getTypeOfExpression(value);
+                var removeNullable = equalsOperator !== assumeTrue && everyType(valueType, function (t) { return !!(t.flags & nullableFlags); }) ||
+                    equalsOperator === assumeTrue && everyType(valueType, function (t) { return !(t.flags & (3 | nullableFlags)); });
+                return removeNullable ? getTypeWithFacts(type, 2097152) : type;
             }
             function narrowTypeByEquality(type, operator, value, assumeTrue) {
                 if (type.flags & 1) {
@@ -45950,10 +45961,6 @@ var ts;
             var assignmentKind = ts.getAssignmentTargetKind(node);
             var apparentType = getApparentType(assignmentKind !== 0 || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType);
             if (ts.isPrivateIdentifier(right)) {
-                if (ts.isOptionalChain(node)) {
-                    grammarErrorOnNode(right, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
-                    return anyType;
-                }
                 checkExternalEmitHelpers(node, 262144);
             }
             var isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType;
@@ -52921,7 +52928,7 @@ var ts;
                 }
                 if (isInstancePropertyWithoutInitializer(member)) {
                     var propName = member.name;
-                    if (ts.isIdentifier(propName)) {
+                    if (ts.isIdentifier(propName) || ts.isPrivateIdentifier(propName)) {
                         var type = getTypeOfSymbol(getSymbolOfNode(member));
                         if (!(type.flags & 3 || getFalsyFlags(type) & 32768)) {
                             if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) {
@@ -55842,28 +55849,30 @@ var ts;
                     default:
                         throw ts.Debug.assertNever(prop, "Unexpected syntax kind:" + prop.kind);
                 }
-                var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
-                if (effectiveName === undefined) {
-                    continue;
-                }
-                var existingKind = seen.get(effectiveName);
-                if (!existingKind) {
-                    seen.set(effectiveName, currentKind);
-                }
-                else {
-                    if ((currentKind & 12) && (existingKind & 12)) {
-                        grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                if (!inDestructuring) {
+                    var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
+                    if (effectiveName === undefined) {
+                        continue;
                     }
-                    else if ((currentKind & 3) && (existingKind & 3)) {
-                        if (existingKind !== 3 && currentKind !== existingKind) {
-                            seen.set(effectiveName, currentKind | existingKind);
-                        }
-                        else {
-                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
-                        }
+                    var existingKind = seen.get(effectiveName);
+                    if (!existingKind) {
+                        seen.set(effectiveName, currentKind);
                     }
                     else {
-                        return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        if ((currentKind & 12) && (existingKind & 12)) {
+                            grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                        }
+                        else if ((currentKind & 3) && (existingKind & 3)) {
+                            if (existingKind !== 3 && currentKind !== existingKind) {
+                                seen.set(effectiveName, currentKind | existingKind);
+                            }
+                            else {
+                                return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
+                            }
+                        }
+                        else {
+                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        }
                     }
                 }
             }
@@ -73257,8 +73266,11 @@ var ts;
 var ts;
 (function (ts) {
     function getDeclarationDiagnostics(host, resolver, file) {
+        if (file && ts.isJsonSourceFile(file)) {
+            return [];
+        }
         var compilerOptions = host.getCompilerOptions();
-        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : host.getSourceFiles(), [transformDeclarations], false);
+        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : ts.filter(host.getSourceFiles(), ts.isSourceFileNotJson), [transformDeclarations], false);
         return result.diagnostics;
     }
     ts.getDeclarationDiagnostics = getDeclarationDiagnostics;
@@ -74803,11 +74815,12 @@ var ts;
         }
         else {
             var ownOutputFilePath = ts.getOwnEmitOutputFilePath(sourceFile.fileName, host, getOutputExtension(sourceFile, options));
-            var isJsonEmittedToSameLocation = ts.isJsonSourceFile(sourceFile) &&
+            var isJsonFile = ts.isJsonSourceFile(sourceFile);
+            var isJsonEmittedToSameLocation = isJsonFile &&
                 ts.comparePaths(sourceFile.fileName, ownOutputFilePath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === 0;
             var jsFilePath = options.emitDeclarationOnly || isJsonEmittedToSameLocation ? undefined : ownOutputFilePath;
             var sourceMapFilePath = !jsFilePath || ts.isJsonSourceFile(sourceFile) ? undefined : getSourceMapFilePath(jsFilePath, options);
-            var declarationFilePath = (forceDtsPaths || ts.getEmitDeclarations(options)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
+            var declarationFilePath = (forceDtsPaths || (ts.getEmitDeclarations(options) && !isJsonFile)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
             var declarationMapPath = declarationFilePath && ts.getAreDeclarationMapsEnabled(options) ? declarationFilePath + ".map" : undefined;
             return { jsFilePath: jsFilePath, sourceMapFilePath: sourceMapFilePath, declarationFilePath: declarationFilePath, declarationMapPath: declarationMapPath, buildInfoPath: undefined };
         }
@@ -74842,7 +74855,7 @@ var ts;
             inputFileName;
     }
     function getOutputDeclarationFileName(inputFileName, configFile, ignoreCase) {
-        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts"));
+        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts") && !ts.fileExtensionIs(inputFileName, ".json"));
         return ts.changeExtension(getOutputPathWithoutChangingExt(inputFileName, configFile, ignoreCase, configFile.options.declarationDir || configFile.options.outDir), ".d.ts");
     }
     ts.getOutputDeclarationFileName = getOutputDeclarationFileName;
@@ -75060,9 +75073,10 @@ var ts;
                 return;
             }
             var sourceFiles = ts.isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;
-            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(sourceFiles, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : sourceFiles;
+            var filesForEmit = forceDtsEmit ? sourceFiles : ts.filter(sourceFiles, ts.isSourceFileNotJson);
+            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(filesForEmit, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : filesForEmit;
             if (emitOnlyDtsFiles && !ts.getEmitDeclarations(compilerOptions)) {
-                sourceFiles.forEach(collectLinkedAliases);
+                filesForEmit.forEach(collectLinkedAliases);
             }
             var declarationTransform = ts.transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, false);
             if (ts.length(declarationTransform.diagnostics)) {
@@ -79877,7 +79891,7 @@ var ts;
                             else if (ts.getEmitModuleKind(parsedRef.commandLine.options) === ts.ModuleKind.None) {
                                 for (var _c = 0, _d = parsedRef.commandLine.fileNames; _c < _d.length; _c++) {
                                     var fileName = _d[_c];
-                                    if (!ts.fileExtensionIs(fileName, ".d.ts")) {
+                                    if (!ts.fileExtensionIs(fileName, ".d.ts") && !ts.fileExtensionIs(fileName, ".json")) {
                                         processSourceFile(ts.getOutputDeclarationFileName(fileName, parsedRef.commandLine, !host.useCaseSensitiveFileNames()), false, false, undefined);
                                     }
                                 }
@@ -81101,7 +81115,7 @@ var ts;
             return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
         }
         function getProjectReferenceRedirectProject(fileName) {
-            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts")) {
+            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts") || ts.fileExtensionIs(fileName, ".json")) {
                 return undefined;
             }
             return getResolvedProjectReferenceToRedirect(fileName);
@@ -81148,7 +81162,7 @@ var ts;
                         }
                         else {
                             ts.forEach(resolvedRef.commandLine.fileNames, function (fileName) {
-                                if (!ts.fileExtensionIs(fileName, ".d.ts")) {
+                                if (!ts.fileExtensionIs(fileName, ".d.ts") && !ts.fileExtensionIs(fileName, ".json")) {
                                     var outputDts = ts.getOutputDeclarationFileName(fileName, resolvedRef.commandLine, host.useCaseSensitiveFileNames());
                                     mapFromToProjectReferenceRedirectSource.set(toPath(outputDts), fileName);
                                 }
diff --git a/lib/tsserver.js b/lib/tsserver.js
index a34dfb219a2..9a1f8fc1191 100644
--- a/lib/tsserver.js
+++ b/lib/tsserver.js
@@ -90,8 +90,8 @@ var __rest = (this && this.__rest) || function (s, e) {
 };
 var ts;
 (function (ts) {
-    // WARNING: The script `configureNightly.ts` uses a regexp to parse out these values.
-    // If changing the text in this section, be sure to test `configureNightly` too.
+    // WARNING: The script `configurePrerelease.ts` uses a regexp to parse out these values.
+    // If changing the text in this section, be sure to test `configurePrerelease` too.
     ts.versionMajorMinor = "3.8";
     /** The version of the TypeScript compiler release */
     ts.version = ts.versionMajorMinor + ".0-beta";
@@ -7192,6 +7192,7 @@ var ts;
         The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access: diag(2779, ts.DiagnosticCategory.Error, "The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access_2779", "The left-hand side of an assignment expression may not be an optional property access."),
         The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access: diag(2780, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access_2780", "The left-hand side of a 'for...in' statement may not be an optional property access."),
         The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access: diag(2781, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access_2781", "The left-hand side of a 'for...of' statement may not be an optional property access."),
+        _0_needs_an_explicit_type_annotation: diag(2782, ts.DiagnosticCategory.Message, "_0_needs_an_explicit_type_annotation_2782", "'{0}' needs an explicit type annotation."),
         Import_declaration_0_is_using_private_name_1: diag(4000, ts.DiagnosticCategory.Error, "Import_declaration_0_is_using_private_name_1_4000", "Import declaration '{0}' is using private name '{1}'."),
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: diag(4002, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_class_has_or_is_using_private_name_1_4002", "Type parameter '{0}' of exported class has or is using private name '{1}'."),
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: diag(4004, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1_4004", "Type parameter '{0}' of exported interface has or is using private name '{1}'."),
@@ -14093,6 +14094,10 @@ var ts;
         return !!node && !!(node.flags & 33554432 /* JsonFile */);
     }
     ts.isInJsonFile = isInJsonFile;
+    function isSourceFileNotJson(file) {
+        return !isJsonSourceFile(file);
+    }
+    ts.isSourceFileNotJson = isSourceFileNotJson;
     function isInJSDoc(node) {
         return !!node && !!(node.flags & 4194304 /* JSDoc */);
     }
@@ -22255,10 +22260,12 @@ var ts;
             var propertyAccess = createNode(194 /* PropertyAccessExpression */, expression.pos);
             propertyAccess.expression = expression;
             propertyAccess.questionDotToken = questionDotToken;
-            // checker will error on private identifiers in optional chains, so don't have to catch them here
             propertyAccess.name = parseRightSideOfDot(/*allowIdentifierNames*/ true, /*allowPrivateIdentifiers*/ true);
             if (questionDotToken || expression.flags & 32 /* OptionalChain */) {
                 propertyAccess.flags |= 32 /* OptionalChain */;
+                if (ts.isPrivateIdentifier(propertyAccess.name)) {
+                    parseErrorAtRange(propertyAccess.name, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
+                }
             }
             return finishNode(propertyAccess);
         }
@@ -31309,7 +31316,7 @@ var ts;
                 ElementKind[ElementKind["Property"] = 1] = "Property";
                 ElementKind[ElementKind["Accessor"] = 2] = "Accessor";
             })(ElementKind || (ElementKind = {}));
-            if (inStrictMode) {
+            if (inStrictMode && !ts.isAssignmentTarget(node)) {
                 var seen = ts.createUnderscoreEscapedMap();
                 for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
                     var prop = _a[_i];
@@ -37714,6 +37721,9 @@ var ts;
                 /*decorators*/ undefined, indexInfo.isReadonly ? [ts.createToken(138 /* ReadonlyKeyword */)] : undefined, [indexingParameter], typeNode);
             }
             function signatureToSignatureDeclarationHelper(signature, kind, context) {
+                var suppressAny = context.flags & 256 /* SuppressAnyReturnType */;
+                if (suppressAny)
+                    context.flags &= ~256 /* SuppressAnyReturnType */; // suppress only toplevel `any`s
                 var typeParameters;
                 var typeArguments;
                 if (context.flags & 32 /* WriteTypeArgumentsOfSignature */ && signature.target && signature.mapper && signature.target.typeParameters) {
@@ -37741,15 +37751,12 @@ var ts;
                 }
                 else {
                     var returnType = getReturnTypeOfSignature(signature);
-                    returnTypeNode = returnType && typeToTypeNodeHelper(returnType, context);
-                }
-                if (context.flags & 256 /* SuppressAnyReturnType */) {
-                    if (returnTypeNode && returnTypeNode.kind === 125 /* AnyKeyword */) {
-                        returnTypeNode = undefined;
+                    if (returnType && !(suppressAny && isTypeAny(returnType))) {
+                        returnTypeNode = typeToTypeNodeHelper(returnType, context);
+                    }
+                    else if (!suppressAny) {
+                        returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                     }
-                }
-                else if (!returnTypeNode) {
-                    returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                 }
                 context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum
                 return ts.createSignatureDeclaration(kind, typeParameters, parameters, returnTypeNode, typeArguments);
@@ -46723,7 +46730,8 @@ var ts;
             return false;
         }
         function isEmptyResolvedType(t) {
-            return t.properties.length === 0 &&
+            return t !== anyFunctionType &&
+                t.properties.length === 0 &&
                 t.callSignatures.length === 0 &&
                 t.constructSignatures.length === 0 &&
                 !t.stringIndexInfo &&
@@ -51127,7 +51135,7 @@ var ts;
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }
@@ -51828,13 +51836,22 @@ var ts;
                 return type;
             }
             function narrowTypeByOptionalChainContainment(type, operator, value, assumeTrue) {
-                // We are in a branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
-                // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
-                // operator is !== and the type of value is undefined.
-                var effectiveTrue = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */ ? assumeTrue : !assumeTrue;
-                var doubleEquals = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */;
-                var valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? 262144 /* EQUndefinedOrNull */ : 65536 /* EQUndefined */));
-                return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
+                // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows:
+                // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch.
+                var equalsOperator = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */;
+                var nullableFlags = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */ ? 98304 /* Nullable */ : 32768 /* Undefined */;
+                var valueType = getTypeOfExpression(value);
+                // Note that we include any and unknown in the exclusion test because their domain includes null and undefined.
+                var removeNullable = equalsOperator !== assumeTrue && everyType(valueType, function (t) { return !!(t.flags & nullableFlags); }) ||
+                    equalsOperator === assumeTrue && everyType(valueType, function (t) { return !(t.flags & (3 /* AnyOrUnknown */ | nullableFlags)); });
+                return removeNullable ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
             }
             function narrowTypeByEquality(type, operator, value, assumeTrue) {
                 if (type.flags & 1 /* Any */) {
@@ -54964,10 +54981,6 @@ var ts;
             var assignmentKind = ts.getAssignmentTargetKind(node);
             var apparentType = getApparentType(assignmentKind !== 0 /* None */ || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType);
             if (ts.isPrivateIdentifier(right)) {
-                if (ts.isOptionalChain(node)) {
-                    grammarErrorOnNode(right, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
-                    return anyType;
-                }
                 checkExternalEmitHelpers(node, 262144 /* ClassPrivateFieldGet */);
             }
             var isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType;
@@ -63212,7 +63225,7 @@ var ts;
                 }
                 if (isInstancePropertyWithoutInitializer(member)) {
                     var propName = member.name;
-                    if (ts.isIdentifier(propName)) {
+                    if (ts.isIdentifier(propName) || ts.isPrivateIdentifier(propName)) {
                         var type = getTypeOfSymbol(getSymbolOfNode(member));
                         if (!(type.flags & 3 /* AnyOrUnknown */ || getFalsyFlags(type) & 32768 /* Undefined */)) {
                             if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) {
@@ -66449,28 +66462,30 @@ var ts;
                     default:
                         throw ts.Debug.assertNever(prop, "Unexpected syntax kind:" + prop.kind);
                 }
-                var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
-                if (effectiveName === undefined) {
-                    continue;
-                }
-                var existingKind = seen.get(effectiveName);
-                if (!existingKind) {
-                    seen.set(effectiveName, currentKind);
-                }
-                else {
-                    if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
-                        grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                if (!inDestructuring) {
+                    var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
+                    if (effectiveName === undefined) {
+                        continue;
                     }
-                    else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
-                        if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
-                            seen.set(effectiveName, currentKind | existingKind);
-                        }
-                        else {
-                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
-                        }
+                    var existingKind = seen.get(effectiveName);
+                    if (!existingKind) {
+                        seen.set(effectiveName, currentKind);
                     }
                     else {
-                        return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
+                            grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                        }
+                        else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
+                            if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
+                                seen.set(effectiveName, currentKind | existingKind);
+                            }
+                            else {
+                                return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
+                            }
+                        }
+                        else {
+                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        }
                     }
                 }
             }
@@ -89726,8 +89741,11 @@ var ts;
 var ts;
 (function (ts) {
     function getDeclarationDiagnostics(host, resolver, file) {
+        if (file && ts.isJsonSourceFile(file)) {
+            return []; // No declaration diagnostics for json for now
+        }
         var compilerOptions = host.getCompilerOptions();
-        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : host.getSourceFiles(), [transformDeclarations], /*allowDtsFiles*/ false);
+        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : ts.filter(host.getSourceFiles(), ts.isSourceFileNotJson), [transformDeclarations], /*allowDtsFiles*/ false);
         return result.diagnostics;
     }
     ts.getDeclarationDiagnostics = getDeclarationDiagnostics;
@@ -91503,12 +91521,13 @@ var ts;
         }
         else {
             var ownOutputFilePath = ts.getOwnEmitOutputFilePath(sourceFile.fileName, host, getOutputExtension(sourceFile, options));
+            var isJsonFile = ts.isJsonSourceFile(sourceFile);
             // If json file emits to the same location skip writing it, if emitDeclarationOnly skip writing it
-            var isJsonEmittedToSameLocation = ts.isJsonSourceFile(sourceFile) &&
+            var isJsonEmittedToSameLocation = isJsonFile &&
                 ts.comparePaths(sourceFile.fileName, ownOutputFilePath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === 0 /* EqualTo */;
             var jsFilePath = options.emitDeclarationOnly || isJsonEmittedToSameLocation ? undefined : ownOutputFilePath;
             var sourceMapFilePath = !jsFilePath || ts.isJsonSourceFile(sourceFile) ? undefined : getSourceMapFilePath(jsFilePath, options);
-            var declarationFilePath = (forceDtsPaths || ts.getEmitDeclarations(options)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
+            var declarationFilePath = (forceDtsPaths || (ts.getEmitDeclarations(options) && !isJsonFile)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
             var declarationMapPath = declarationFilePath && ts.getAreDeclarationMapsEnabled(options) ? declarationFilePath + ".map" : undefined;
             return { jsFilePath: jsFilePath, sourceMapFilePath: sourceMapFilePath, declarationFilePath: declarationFilePath, declarationMapPath: declarationMapPath, buildInfoPath: undefined };
         }
@@ -91549,7 +91568,7 @@ var ts;
     }
     /* @internal */
     function getOutputDeclarationFileName(inputFileName, configFile, ignoreCase) {
-        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */));
+        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(inputFileName, ".json" /* Json */));
         return ts.changeExtension(getOutputPathWithoutChangingExt(inputFileName, configFile, ignoreCase, configFile.options.declarationDir || configFile.options.outDir), ".d.ts" /* Dts */);
     }
     ts.getOutputDeclarationFileName = getOutputDeclarationFileName;
@@ -91779,12 +91798,13 @@ var ts;
                 return;
             }
             var sourceFiles = ts.isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;
+            var filesForEmit = forceDtsEmit ? sourceFiles : ts.filter(sourceFiles, ts.isSourceFileNotJson);
             // Setup and perform the transformation to retrieve declarations from the input files
-            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(sourceFiles, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : sourceFiles;
+            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(filesForEmit, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : filesForEmit;
             if (emitOnlyDtsFiles && !ts.getEmitDeclarations(compilerOptions)) {
                 // Checker wont collect the linked aliases since thats only done when declaration is enabled.
                 // Do that here when emitting only dts files
-                sourceFiles.forEach(collectLinkedAliases);
+                filesForEmit.forEach(collectLinkedAliases);
             }
             var declarationTransform = ts.transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, /*allowDtsFiles*/ false);
             if (ts.length(declarationTransform.diagnostics)) {
@@ -97071,7 +97091,7 @@ var ts;
                             else if (ts.getEmitModuleKind(parsedRef.commandLine.options) === ts.ModuleKind.None) {
                                 for (var _c = 0, _d = parsedRef.commandLine.fileNames; _c < _d.length; _c++) {
                                     var fileName = _d[_c];
-                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                         processSourceFile(ts.getOutputDeclarationFileName(fileName, parsedRef.commandLine, !host.useCaseSensitiveFileNames()), /*isDefaultLib*/ false, /*ignoreNoDefaultLib*/ false, /*packageId*/ undefined);
                                     }
                                 }
@@ -98496,8 +98516,8 @@ var ts;
             return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
         }
         function getProjectReferenceRedirectProject(fileName) {
-            // Ignore dts
-            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+            // Ignore dts or any json files
+            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) || ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                 return undefined;
             }
             // If this file is produced by a referenced project, we need to rewrite it to
@@ -98551,7 +98571,7 @@ var ts;
                         }
                         else {
                             ts.forEach(resolvedRef.commandLine.fileNames, function (fileName) {
-                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                     var outputDts = ts.getOutputDeclarationFileName(fileName, resolvedRef.commandLine, host.useCaseSensitiveFileNames());
                                     mapFromToProjectReferenceRedirectSource.set(toPath(outputDts), fileName);
                                 }
@@ -110064,7 +110084,7 @@ var ts;
                 switch (contextToken.kind) {
                     case 27 /* CommaToken */:
                         return containingNodeKind === 242 /* VariableDeclaration */ ||
-                            containingNodeKind === 243 /* VariableDeclarationList */ ||
+                            isVariableDeclarationListButNotTypeArgument(contextToken) ||
                             containingNodeKind === 225 /* VariableStatement */ ||
                             containingNodeKind === 248 /* EnumDeclaration */ || // enum a { foo, |
                             isFunctionLikeButNotConstructor(containingNodeKind) ||
@@ -110175,6 +110195,10 @@ var ts;
                 }
                 return false;
             }
+            function isVariableDeclarationListButNotTypeArgument(node) {
+                return node.parent.kind === 243 /* VariableDeclarationList */
+                    && !ts.isPossiblyTypeArgumentPosition(node, sourceFile, typeChecker);
+            }
             /**
              * Filters out completion suggestions for named imports or exports.
              *
@@ -138440,6 +138464,7 @@ var ts;
                     scriptInfo.attachToProject(_this);
                 }, function (removed) { return _this.detachScriptInfoFromProject(removed); });
                 var elapsed = ts.timestamp() - start;
+                this.projectService.sendUpdateGraphPerformanceEvent(elapsed);
                 this.writeLog("Finishing updateGraphWorker: Project: " + this.getProjectName() + " Version: " + this.getProjectVersion() + " structureChanged: " + hasNewProgram + " Elapsed: " + elapsed + "ms");
                 if (this.hasAddedorRemovedFiles) {
                     this.print();
@@ -139875,6 +139900,12 @@ var ts;
                 this.eventHandler(event);
             };
             /* @internal */
+            ProjectService.prototype.sendUpdateGraphPerformanceEvent = function (durationMs) {
+                if (this.performanceEventHandler) {
+                    this.performanceEventHandler({ kind: "UpdateGraph", durationMs: durationMs });
+                }
+            };
+            /* @internal */
             ProjectService.prototype.delayUpdateProjectGraphAndEnsureProjectStructureForOpenFiles = function (project) {
                 this.delayUpdateProjectGraph(project);
                 this.delayEnsureProjectForOpenFiles();
@@ -141357,6 +141388,10 @@ var ts;
                 }
                 return info.sourceFileLike;
             };
+            /*@internal*/
+            ProjectService.prototype.setPerformanceEventHandler = function (performanceEventHandler) {
+                this.performanceEventHandler = performanceEventHandler;
+            };
             ProjectService.prototype.setHostConfiguration = function (args) {
                 var _this = this;
                 if (args.file) {
@@ -143107,11 +143142,20 @@ var ts;
                     syntaxOnly: opts.syntaxOnly,
                 };
                 this.projectService = new server.ProjectService(settings);
+                this.projectService.setPerformanceEventHandler(this.performanceEventHandler.bind(this));
                 this.gcTimer = new server.GcTimer(this.host, /*delay*/ 7000, this.logger);
             }
             Session.prototype.sendRequestCompletedEvent = function (requestId) {
                 this.event({ request_seq: requestId }, "requestCompleted");
             };
+            Session.prototype.performanceEventHandler = function (event) {
+                switch (event.kind) {
+                    case "UpdateGraph": {
+                        this.updateGraphDurationMs = (this.updateGraphDurationMs || 0) + event.durationMs;
+                        break;
+                    }
+                }
+            };
             Session.prototype.defaultEventHandler = function (event) {
                 switch (event.eventName) {
                     case server.ProjectsUpdatedInBackgroundEvent:
@@ -143238,6 +143282,7 @@ var ts;
                     command: cmdName,
                     request_seq: reqSeq,
                     success: success,
+                    updateGraphDurationMs: this.updateGraphDurationMs,
                 };
                 if (success) {
                     var metadata = void 0;
@@ -144498,6 +144543,7 @@ var ts;
             };
             Session.prototype.onMessage = function (message) {
                 this.gcTimer.scheduleCollect();
+                this.updateGraphDurationMs = undefined;
                 var start;
                 if (this.logger.hasLevel(server.LogLevel.requestTime)) {
                     start = this.hrtime();
diff --git a/lib/tsserverlibrary.d.ts b/lib/tsserverlibrary.d.ts
index 5ca50db8067..1855fae39b6 100644
--- a/lib/tsserverlibrary.d.ts
+++ b/lib/tsserverlibrary.d.ts
@@ -9154,6 +9154,7 @@ declare namespace ts.server {
         readonly syntaxOnly?: boolean;
         /** Tracks projects that we have already sent telemetry for. */
         private readonly seenProjects;
+        private performanceEventHandler?;
         constructor(opts: ProjectServiceOptions);
         toPath(fileName: string): Path;
         private loadTypesMap;
@@ -9383,6 +9384,7 @@ declare namespace ts.server {
         private readonly gcTimer;
         protected projectService: ProjectService;
         private changeSeq;
+        private updateGraphDurationMs;
         private currentRequestId;
         private errorCheck;
         protected host: ServerHost;
@@ -9397,6 +9399,7 @@ declare namespace ts.server {
         private readonly noGetErrOnBackgroundUpdate?;
         constructor(opts: SessionOptions);
         private sendRequestCompletedEvent;
+        private performanceEventHandler;
         private defaultEventHandler;
         private projectsUpdatedInBackgroundEvent;
         logError(err: Error, cmd: string): void;
diff --git a/lib/tsserverlibrary.js b/lib/tsserverlibrary.js
index c95ff9cd8e9..453cb80dbbf 100644
--- a/lib/tsserverlibrary.js
+++ b/lib/tsserverlibrary.js
@@ -240,8 +240,8 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    // WARNING: The script `configureNightly.ts` uses a regexp to parse out these values.
-    // If changing the text in this section, be sure to test `configureNightly` too.
+    // WARNING: The script `configurePrerelease.ts` uses a regexp to parse out these values.
+    // If changing the text in this section, be sure to test `configurePrerelease` too.
     ts.versionMajorMinor = "3.8";
     /** The version of the TypeScript compiler release */
     ts.version = ts.versionMajorMinor + ".0-beta";
@@ -7342,6 +7342,7 @@ var ts;
         The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access: diag(2779, ts.DiagnosticCategory.Error, "The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access_2779", "The left-hand side of an assignment expression may not be an optional property access."),
         The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access: diag(2780, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access_2780", "The left-hand side of a 'for...in' statement may not be an optional property access."),
         The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access: diag(2781, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access_2781", "The left-hand side of a 'for...of' statement may not be an optional property access."),
+        _0_needs_an_explicit_type_annotation: diag(2782, ts.DiagnosticCategory.Message, "_0_needs_an_explicit_type_annotation_2782", "'{0}' needs an explicit type annotation."),
         Import_declaration_0_is_using_private_name_1: diag(4000, ts.DiagnosticCategory.Error, "Import_declaration_0_is_using_private_name_1_4000", "Import declaration '{0}' is using private name '{1}'."),
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: diag(4002, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_class_has_or_is_using_private_name_1_4002", "Type parameter '{0}' of exported class has or is using private name '{1}'."),
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: diag(4004, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1_4004", "Type parameter '{0}' of exported interface has or is using private name '{1}'."),
@@ -14243,6 +14244,10 @@ var ts;
         return !!node && !!(node.flags & 33554432 /* JsonFile */);
     }
     ts.isInJsonFile = isInJsonFile;
+    function isSourceFileNotJson(file) {
+        return !isJsonSourceFile(file);
+    }
+    ts.isSourceFileNotJson = isSourceFileNotJson;
     function isInJSDoc(node) {
         return !!node && !!(node.flags & 4194304 /* JSDoc */);
     }
@@ -22405,10 +22410,12 @@ var ts;
             var propertyAccess = createNode(194 /* PropertyAccessExpression */, expression.pos);
             propertyAccess.expression = expression;
             propertyAccess.questionDotToken = questionDotToken;
-            // checker will error on private identifiers in optional chains, so don't have to catch them here
             propertyAccess.name = parseRightSideOfDot(/*allowIdentifierNames*/ true, /*allowPrivateIdentifiers*/ true);
             if (questionDotToken || expression.flags & 32 /* OptionalChain */) {
                 propertyAccess.flags |= 32 /* OptionalChain */;
+                if (ts.isPrivateIdentifier(propertyAccess.name)) {
+                    parseErrorAtRange(propertyAccess.name, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
+                }
             }
             return finishNode(propertyAccess);
         }
@@ -31459,7 +31466,7 @@ var ts;
                 ElementKind[ElementKind["Property"] = 1] = "Property";
                 ElementKind[ElementKind["Accessor"] = 2] = "Accessor";
             })(ElementKind || (ElementKind = {}));
-            if (inStrictMode) {
+            if (inStrictMode && !ts.isAssignmentTarget(node)) {
                 var seen = ts.createUnderscoreEscapedMap();
                 for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
                     var prop = _a[_i];
@@ -37864,6 +37871,9 @@ var ts;
                 /*decorators*/ undefined, indexInfo.isReadonly ? [ts.createToken(138 /* ReadonlyKeyword */)] : undefined, [indexingParameter], typeNode);
             }
             function signatureToSignatureDeclarationHelper(signature, kind, context) {
+                var suppressAny = context.flags & 256 /* SuppressAnyReturnType */;
+                if (suppressAny)
+                    context.flags &= ~256 /* SuppressAnyReturnType */; // suppress only toplevel `any`s
                 var typeParameters;
                 var typeArguments;
                 if (context.flags & 32 /* WriteTypeArgumentsOfSignature */ && signature.target && signature.mapper && signature.target.typeParameters) {
@@ -37891,15 +37901,12 @@ var ts;
                 }
                 else {
                     var returnType = getReturnTypeOfSignature(signature);
-                    returnTypeNode = returnType && typeToTypeNodeHelper(returnType, context);
-                }
-                if (context.flags & 256 /* SuppressAnyReturnType */) {
-                    if (returnTypeNode && returnTypeNode.kind === 125 /* AnyKeyword */) {
-                        returnTypeNode = undefined;
+                    if (returnType && !(suppressAny && isTypeAny(returnType))) {
+                        returnTypeNode = typeToTypeNodeHelper(returnType, context);
+                    }
+                    else if (!suppressAny) {
+                        returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                     }
-                }
-                else if (!returnTypeNode) {
-                    returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                 }
                 context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum
                 return ts.createSignatureDeclaration(kind, typeParameters, parameters, returnTypeNode, typeArguments);
@@ -46873,7 +46880,8 @@ var ts;
             return false;
         }
         function isEmptyResolvedType(t) {
-            return t.properties.length === 0 &&
+            return t !== anyFunctionType &&
+                t.properties.length === 0 &&
                 t.callSignatures.length === 0 &&
                 t.constructSignatures.length === 0 &&
                 !t.stringIndexInfo &&
@@ -51277,7 +51285,7 @@ var ts;
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }
@@ -51978,13 +51986,22 @@ var ts;
                 return type;
             }
             function narrowTypeByOptionalChainContainment(type, operator, value, assumeTrue) {
-                // We are in a branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
-                // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
-                // operator is !== and the type of value is undefined.
-                var effectiveTrue = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */ ? assumeTrue : !assumeTrue;
-                var doubleEquals = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */;
-                var valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? 262144 /* EQUndefinedOrNull */ : 65536 /* EQUndefined */));
-                return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
+                // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows:
+                // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch.
+                var equalsOperator = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */;
+                var nullableFlags = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */ ? 98304 /* Nullable */ : 32768 /* Undefined */;
+                var valueType = getTypeOfExpression(value);
+                // Note that we include any and unknown in the exclusion test because their domain includes null and undefined.
+                var removeNullable = equalsOperator !== assumeTrue && everyType(valueType, function (t) { return !!(t.flags & nullableFlags); }) ||
+                    equalsOperator === assumeTrue && everyType(valueType, function (t) { return !(t.flags & (3 /* AnyOrUnknown */ | nullableFlags)); });
+                return removeNullable ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
             }
             function narrowTypeByEquality(type, operator, value, assumeTrue) {
                 if (type.flags & 1 /* Any */) {
@@ -55114,10 +55131,6 @@ var ts;
             var assignmentKind = ts.getAssignmentTargetKind(node);
             var apparentType = getApparentType(assignmentKind !== 0 /* None */ || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType);
             if (ts.isPrivateIdentifier(right)) {
-                if (ts.isOptionalChain(node)) {
-                    grammarErrorOnNode(right, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
-                    return anyType;
-                }
                 checkExternalEmitHelpers(node, 262144 /* ClassPrivateFieldGet */);
             }
             var isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType;
@@ -63362,7 +63375,7 @@ var ts;
                 }
                 if (isInstancePropertyWithoutInitializer(member)) {
                     var propName = member.name;
-                    if (ts.isIdentifier(propName)) {
+                    if (ts.isIdentifier(propName) || ts.isPrivateIdentifier(propName)) {
                         var type = getTypeOfSymbol(getSymbolOfNode(member));
                         if (!(type.flags & 3 /* AnyOrUnknown */ || getFalsyFlags(type) & 32768 /* Undefined */)) {
                             if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) {
@@ -66599,28 +66612,30 @@ var ts;
                     default:
                         throw ts.Debug.assertNever(prop, "Unexpected syntax kind:" + prop.kind);
                 }
-                var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
-                if (effectiveName === undefined) {
-                    continue;
-                }
-                var existingKind = seen.get(effectiveName);
-                if (!existingKind) {
-                    seen.set(effectiveName, currentKind);
-                }
-                else {
-                    if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
-                        grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                if (!inDestructuring) {
+                    var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
+                    if (effectiveName === undefined) {
+                        continue;
                     }
-                    else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
-                        if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
-                            seen.set(effectiveName, currentKind | existingKind);
-                        }
-                        else {
-                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
-                        }
+                    var existingKind = seen.get(effectiveName);
+                    if (!existingKind) {
+                        seen.set(effectiveName, currentKind);
                     }
                     else {
-                        return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
+                            grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                        }
+                        else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
+                            if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
+                                seen.set(effectiveName, currentKind | existingKind);
+                            }
+                            else {
+                                return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
+                            }
+                        }
+                        else {
+                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        }
                     }
                 }
             }
@@ -89876,8 +89891,11 @@ var ts;
 var ts;
 (function (ts) {
     function getDeclarationDiagnostics(host, resolver, file) {
+        if (file && ts.isJsonSourceFile(file)) {
+            return []; // No declaration diagnostics for json for now
+        }
         var compilerOptions = host.getCompilerOptions();
-        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : host.getSourceFiles(), [transformDeclarations], /*allowDtsFiles*/ false);
+        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : ts.filter(host.getSourceFiles(), ts.isSourceFileNotJson), [transformDeclarations], /*allowDtsFiles*/ false);
         return result.diagnostics;
     }
     ts.getDeclarationDiagnostics = getDeclarationDiagnostics;
@@ -91653,12 +91671,13 @@ var ts;
         }
         else {
             var ownOutputFilePath = ts.getOwnEmitOutputFilePath(sourceFile.fileName, host, getOutputExtension(sourceFile, options));
+            var isJsonFile = ts.isJsonSourceFile(sourceFile);
             // If json file emits to the same location skip writing it, if emitDeclarationOnly skip writing it
-            var isJsonEmittedToSameLocation = ts.isJsonSourceFile(sourceFile) &&
+            var isJsonEmittedToSameLocation = isJsonFile &&
                 ts.comparePaths(sourceFile.fileName, ownOutputFilePath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === 0 /* EqualTo */;
             var jsFilePath = options.emitDeclarationOnly || isJsonEmittedToSameLocation ? undefined : ownOutputFilePath;
             var sourceMapFilePath = !jsFilePath || ts.isJsonSourceFile(sourceFile) ? undefined : getSourceMapFilePath(jsFilePath, options);
-            var declarationFilePath = (forceDtsPaths || ts.getEmitDeclarations(options)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
+            var declarationFilePath = (forceDtsPaths || (ts.getEmitDeclarations(options) && !isJsonFile)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
             var declarationMapPath = declarationFilePath && ts.getAreDeclarationMapsEnabled(options) ? declarationFilePath + ".map" : undefined;
             return { jsFilePath: jsFilePath, sourceMapFilePath: sourceMapFilePath, declarationFilePath: declarationFilePath, declarationMapPath: declarationMapPath, buildInfoPath: undefined };
         }
@@ -91699,7 +91718,7 @@ var ts;
     }
     /* @internal */
     function getOutputDeclarationFileName(inputFileName, configFile, ignoreCase) {
-        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */));
+        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(inputFileName, ".json" /* Json */));
         return ts.changeExtension(getOutputPathWithoutChangingExt(inputFileName, configFile, ignoreCase, configFile.options.declarationDir || configFile.options.outDir), ".d.ts" /* Dts */);
     }
     ts.getOutputDeclarationFileName = getOutputDeclarationFileName;
@@ -91929,12 +91948,13 @@ var ts;
                 return;
             }
             var sourceFiles = ts.isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;
+            var filesForEmit = forceDtsEmit ? sourceFiles : ts.filter(sourceFiles, ts.isSourceFileNotJson);
             // Setup and perform the transformation to retrieve declarations from the input files
-            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(sourceFiles, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : sourceFiles;
+            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(filesForEmit, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : filesForEmit;
             if (emitOnlyDtsFiles && !ts.getEmitDeclarations(compilerOptions)) {
                 // Checker wont collect the linked aliases since thats only done when declaration is enabled.
                 // Do that here when emitting only dts files
-                sourceFiles.forEach(collectLinkedAliases);
+                filesForEmit.forEach(collectLinkedAliases);
             }
             var declarationTransform = ts.transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, /*allowDtsFiles*/ false);
             if (ts.length(declarationTransform.diagnostics)) {
@@ -97221,7 +97241,7 @@ var ts;
                             else if (ts.getEmitModuleKind(parsedRef.commandLine.options) === ts.ModuleKind.None) {
                                 for (var _c = 0, _d = parsedRef.commandLine.fileNames; _c < _d.length; _c++) {
                                     var fileName = _d[_c];
-                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                         processSourceFile(ts.getOutputDeclarationFileName(fileName, parsedRef.commandLine, !host.useCaseSensitiveFileNames()), /*isDefaultLib*/ false, /*ignoreNoDefaultLib*/ false, /*packageId*/ undefined);
                                     }
                                 }
@@ -98646,8 +98666,8 @@ var ts;
             return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
         }
         function getProjectReferenceRedirectProject(fileName) {
-            // Ignore dts
-            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+            // Ignore dts or any json files
+            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) || ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                 return undefined;
             }
             // If this file is produced by a referenced project, we need to rewrite it to
@@ -98701,7 +98721,7 @@ var ts;
                         }
                         else {
                             ts.forEach(resolvedRef.commandLine.fileNames, function (fileName) {
-                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                     var outputDts = ts.getOutputDeclarationFileName(fileName, resolvedRef.commandLine, host.useCaseSensitiveFileNames());
                                     mapFromToProjectReferenceRedirectSource.set(toPath(outputDts), fileName);
                                 }
@@ -110587,7 +110607,7 @@ var ts;
                 switch (contextToken.kind) {
                     case 27 /* CommaToken */:
                         return containingNodeKind === 242 /* VariableDeclaration */ ||
-                            containingNodeKind === 243 /* VariableDeclarationList */ ||
+                            isVariableDeclarationListButNotTypeArgument(contextToken) ||
                             containingNodeKind === 225 /* VariableStatement */ ||
                             containingNodeKind === 248 /* EnumDeclaration */ || // enum a { foo, |
                             isFunctionLikeButNotConstructor(containingNodeKind) ||
@@ -110698,6 +110718,10 @@ var ts;
                 }
                 return false;
             }
+            function isVariableDeclarationListButNotTypeArgument(node) {
+                return node.parent.kind === 243 /* VariableDeclarationList */
+                    && !ts.isPossiblyTypeArgumentPosition(node, sourceFile, typeChecker);
+            }
             /**
              * Filters out completion suggestions for named imports or exports.
              *
@@ -138590,6 +138614,7 @@ var ts;
                     scriptInfo.attachToProject(_this);
                 }, function (removed) { return _this.detachScriptInfoFromProject(removed); });
                 var elapsed = ts.timestamp() - start;
+                this.projectService.sendUpdateGraphPerformanceEvent(elapsed);
                 this.writeLog("Finishing updateGraphWorker: Project: " + this.getProjectName() + " Version: " + this.getProjectVersion() + " structureChanged: " + hasNewProgram + " Elapsed: " + elapsed + "ms");
                 if (this.hasAddedorRemovedFiles) {
                     this.print();
@@ -140025,6 +140050,12 @@ var ts;
                 this.eventHandler(event);
             };
             /* @internal */
+            ProjectService.prototype.sendUpdateGraphPerformanceEvent = function (durationMs) {
+                if (this.performanceEventHandler) {
+                    this.performanceEventHandler({ kind: "UpdateGraph", durationMs: durationMs });
+                }
+            };
+            /* @internal */
             ProjectService.prototype.delayUpdateProjectGraphAndEnsureProjectStructureForOpenFiles = function (project) {
                 this.delayUpdateProjectGraph(project);
                 this.delayEnsureProjectForOpenFiles();
@@ -141507,6 +141538,10 @@ var ts;
                 }
                 return info.sourceFileLike;
             };
+            /*@internal*/
+            ProjectService.prototype.setPerformanceEventHandler = function (performanceEventHandler) {
+                this.performanceEventHandler = performanceEventHandler;
+            };
             ProjectService.prototype.setHostConfiguration = function (args) {
                 var _this = this;
                 if (args.file) {
@@ -143257,11 +143292,20 @@ var ts;
                     syntaxOnly: opts.syntaxOnly,
                 };
                 this.projectService = new server.ProjectService(settings);
+                this.projectService.setPerformanceEventHandler(this.performanceEventHandler.bind(this));
                 this.gcTimer = new server.GcTimer(this.host, /*delay*/ 7000, this.logger);
             }
             Session.prototype.sendRequestCompletedEvent = function (requestId) {
                 this.event({ request_seq: requestId }, "requestCompleted");
             };
+            Session.prototype.performanceEventHandler = function (event) {
+                switch (event.kind) {
+                    case "UpdateGraph": {
+                        this.updateGraphDurationMs = (this.updateGraphDurationMs || 0) + event.durationMs;
+                        break;
+                    }
+                }
+            };
             Session.prototype.defaultEventHandler = function (event) {
                 switch (event.eventName) {
                     case server.ProjectsUpdatedInBackgroundEvent:
@@ -143388,6 +143432,7 @@ var ts;
                     command: cmdName,
                     request_seq: reqSeq,
                     success: success,
+                    updateGraphDurationMs: this.updateGraphDurationMs,
                 };
                 if (success) {
                     var metadata = void 0;
@@ -144648,6 +144693,7 @@ var ts;
             };
             Session.prototype.onMessage = function (message) {
                 this.gcTimer.scheduleCollect();
+                this.updateGraphDurationMs = undefined;
                 var start;
                 if (this.logger.hasLevel(server.LogLevel.requestTime)) {
                     start = this.hrtime();
diff --git a/lib/typescript.js b/lib/typescript.js
index cc5ccbfe84b..c58724a0d0d 100644
--- a/lib/typescript.js
+++ b/lib/typescript.js
@@ -229,8 +229,8 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    // WARNING: The script `configureNightly.ts` uses a regexp to parse out these values.
-    // If changing the text in this section, be sure to test `configureNightly` too.
+    // WARNING: The script `configurePrerelease.ts` uses a regexp to parse out these values.
+    // If changing the text in this section, be sure to test `configurePrerelease` too.
     ts.versionMajorMinor = "3.8";
     /** The version of the TypeScript compiler release */
     ts.version = ts.versionMajorMinor + ".0-beta";
@@ -7331,6 +7331,7 @@ var ts;
         The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access: diag(2779, ts.DiagnosticCategory.Error, "The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access_2779", "The left-hand side of an assignment expression may not be an optional property access."),
         The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access: diag(2780, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access_2780", "The left-hand side of a 'for...in' statement may not be an optional property access."),
         The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access: diag(2781, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access_2781", "The left-hand side of a 'for...of' statement may not be an optional property access."),
+        _0_needs_an_explicit_type_annotation: diag(2782, ts.DiagnosticCategory.Message, "_0_needs_an_explicit_type_annotation_2782", "'{0}' needs an explicit type annotation."),
         Import_declaration_0_is_using_private_name_1: diag(4000, ts.DiagnosticCategory.Error, "Import_declaration_0_is_using_private_name_1_4000", "Import declaration '{0}' is using private name '{1}'."),
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: diag(4002, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_class_has_or_is_using_private_name_1_4002", "Type parameter '{0}' of exported class has or is using private name '{1}'."),
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: diag(4004, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1_4004", "Type parameter '{0}' of exported interface has or is using private name '{1}'."),
@@ -14232,6 +14233,10 @@ var ts;
         return !!node && !!(node.flags & 33554432 /* JsonFile */);
     }
     ts.isInJsonFile = isInJsonFile;
+    function isSourceFileNotJson(file) {
+        return !isJsonSourceFile(file);
+    }
+    ts.isSourceFileNotJson = isSourceFileNotJson;
     function isInJSDoc(node) {
         return !!node && !!(node.flags & 4194304 /* JSDoc */);
     }
@@ -22394,10 +22399,12 @@ var ts;
             var propertyAccess = createNode(194 /* PropertyAccessExpression */, expression.pos);
             propertyAccess.expression = expression;
             propertyAccess.questionDotToken = questionDotToken;
-            // checker will error on private identifiers in optional chains, so don't have to catch them here
             propertyAccess.name = parseRightSideOfDot(/*allowIdentifierNames*/ true, /*allowPrivateIdentifiers*/ true);
             if (questionDotToken || expression.flags & 32 /* OptionalChain */) {
                 propertyAccess.flags |= 32 /* OptionalChain */;
+                if (ts.isPrivateIdentifier(propertyAccess.name)) {
+                    parseErrorAtRange(propertyAccess.name, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
+                }
             }
             return finishNode(propertyAccess);
         }
@@ -31448,7 +31455,7 @@ var ts;
                 ElementKind[ElementKind["Property"] = 1] = "Property";
                 ElementKind[ElementKind["Accessor"] = 2] = "Accessor";
             })(ElementKind || (ElementKind = {}));
-            if (inStrictMode) {
+            if (inStrictMode && !ts.isAssignmentTarget(node)) {
                 var seen = ts.createUnderscoreEscapedMap();
                 for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
                     var prop = _a[_i];
@@ -37853,6 +37860,9 @@ var ts;
                 /*decorators*/ undefined, indexInfo.isReadonly ? [ts.createToken(138 /* ReadonlyKeyword */)] : undefined, [indexingParameter], typeNode);
             }
             function signatureToSignatureDeclarationHelper(signature, kind, context) {
+                var suppressAny = context.flags & 256 /* SuppressAnyReturnType */;
+                if (suppressAny)
+                    context.flags &= ~256 /* SuppressAnyReturnType */; // suppress only toplevel `any`s
                 var typeParameters;
                 var typeArguments;
                 if (context.flags & 32 /* WriteTypeArgumentsOfSignature */ && signature.target && signature.mapper && signature.target.typeParameters) {
@@ -37880,15 +37890,12 @@ var ts;
                 }
                 else {
                     var returnType = getReturnTypeOfSignature(signature);
-                    returnTypeNode = returnType && typeToTypeNodeHelper(returnType, context);
-                }
-                if (context.flags & 256 /* SuppressAnyReturnType */) {
-                    if (returnTypeNode && returnTypeNode.kind === 125 /* AnyKeyword */) {
-                        returnTypeNode = undefined;
+                    if (returnType && !(suppressAny && isTypeAny(returnType))) {
+                        returnTypeNode = typeToTypeNodeHelper(returnType, context);
+                    }
+                    else if (!suppressAny) {
+                        returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                     }
-                }
-                else if (!returnTypeNode) {
-                    returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                 }
                 context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum
                 return ts.createSignatureDeclaration(kind, typeParameters, parameters, returnTypeNode, typeArguments);
@@ -46862,7 +46869,8 @@ var ts;
             return false;
         }
         function isEmptyResolvedType(t) {
-            return t.properties.length === 0 &&
+            return t !== anyFunctionType &&
+                t.properties.length === 0 &&
                 t.callSignatures.length === 0 &&
                 t.constructSignatures.length === 0 &&
                 !t.stringIndexInfo &&
@@ -51266,7 +51274,7 @@ var ts;
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }
@@ -51967,13 +51975,22 @@ var ts;
                 return type;
             }
             function narrowTypeByOptionalChainContainment(type, operator, value, assumeTrue) {
-                // We are in a branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
-                // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
-                // operator is !== and the type of value is undefined.
-                var effectiveTrue = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */ ? assumeTrue : !assumeTrue;
-                var doubleEquals = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */;
-                var valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? 262144 /* EQUndefinedOrNull */ : 65536 /* EQUndefined */));
-                return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
+                // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows:
+                // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch.
+                var equalsOperator = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */;
+                var nullableFlags = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */ ? 98304 /* Nullable */ : 32768 /* Undefined */;
+                var valueType = getTypeOfExpression(value);
+                // Note that we include any and unknown in the exclusion test because their domain includes null and undefined.
+                var removeNullable = equalsOperator !== assumeTrue && everyType(valueType, function (t) { return !!(t.flags & nullableFlags); }) ||
+                    equalsOperator === assumeTrue && everyType(valueType, function (t) { return !(t.flags & (3 /* AnyOrUnknown */ | nullableFlags)); });
+                return removeNullable ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
             }
             function narrowTypeByEquality(type, operator, value, assumeTrue) {
                 if (type.flags & 1 /* Any */) {
@@ -55103,10 +55120,6 @@ var ts;
             var assignmentKind = ts.getAssignmentTargetKind(node);
             var apparentType = getApparentType(assignmentKind !== 0 /* None */ || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType);
             if (ts.isPrivateIdentifier(right)) {
-                if (ts.isOptionalChain(node)) {
-                    grammarErrorOnNode(right, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
-                    return anyType;
-                }
                 checkExternalEmitHelpers(node, 262144 /* ClassPrivateFieldGet */);
             }
             var isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType;
@@ -63351,7 +63364,7 @@ var ts;
                 }
                 if (isInstancePropertyWithoutInitializer(member)) {
                     var propName = member.name;
-                    if (ts.isIdentifier(propName)) {
+                    if (ts.isIdentifier(propName) || ts.isPrivateIdentifier(propName)) {
                         var type = getTypeOfSymbol(getSymbolOfNode(member));
                         if (!(type.flags & 3 /* AnyOrUnknown */ || getFalsyFlags(type) & 32768 /* Undefined */)) {
                             if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) {
@@ -66588,28 +66601,30 @@ var ts;
                     default:
                         throw ts.Debug.assertNever(prop, "Unexpected syntax kind:" + prop.kind);
                 }
-                var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
-                if (effectiveName === undefined) {
-                    continue;
-                }
-                var existingKind = seen.get(effectiveName);
-                if (!existingKind) {
-                    seen.set(effectiveName, currentKind);
-                }
-                else {
-                    if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
-                        grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                if (!inDestructuring) {
+                    var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
+                    if (effectiveName === undefined) {
+                        continue;
                     }
-                    else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
-                        if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
-                            seen.set(effectiveName, currentKind | existingKind);
-                        }
-                        else {
-                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
-                        }
+                    var existingKind = seen.get(effectiveName);
+                    if (!existingKind) {
+                        seen.set(effectiveName, currentKind);
                     }
                     else {
-                        return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
+                            grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                        }
+                        else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
+                            if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
+                                seen.set(effectiveName, currentKind | existingKind);
+                            }
+                            else {
+                                return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
+                            }
+                        }
+                        else {
+                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        }
                     }
                 }
             }
@@ -89865,8 +89880,11 @@ var ts;
 var ts;
 (function (ts) {
     function getDeclarationDiagnostics(host, resolver, file) {
+        if (file && ts.isJsonSourceFile(file)) {
+            return []; // No declaration diagnostics for json for now
+        }
         var compilerOptions = host.getCompilerOptions();
-        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : host.getSourceFiles(), [transformDeclarations], /*allowDtsFiles*/ false);
+        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : ts.filter(host.getSourceFiles(), ts.isSourceFileNotJson), [transformDeclarations], /*allowDtsFiles*/ false);
         return result.diagnostics;
     }
     ts.getDeclarationDiagnostics = getDeclarationDiagnostics;
@@ -91642,12 +91660,13 @@ var ts;
         }
         else {
             var ownOutputFilePath = ts.getOwnEmitOutputFilePath(sourceFile.fileName, host, getOutputExtension(sourceFile, options));
+            var isJsonFile = ts.isJsonSourceFile(sourceFile);
             // If json file emits to the same location skip writing it, if emitDeclarationOnly skip writing it
-            var isJsonEmittedToSameLocation = ts.isJsonSourceFile(sourceFile) &&
+            var isJsonEmittedToSameLocation = isJsonFile &&
                 ts.comparePaths(sourceFile.fileName, ownOutputFilePath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === 0 /* EqualTo */;
             var jsFilePath = options.emitDeclarationOnly || isJsonEmittedToSameLocation ? undefined : ownOutputFilePath;
             var sourceMapFilePath = !jsFilePath || ts.isJsonSourceFile(sourceFile) ? undefined : getSourceMapFilePath(jsFilePath, options);
-            var declarationFilePath = (forceDtsPaths || ts.getEmitDeclarations(options)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
+            var declarationFilePath = (forceDtsPaths || (ts.getEmitDeclarations(options) && !isJsonFile)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
             var declarationMapPath = declarationFilePath && ts.getAreDeclarationMapsEnabled(options) ? declarationFilePath + ".map" : undefined;
             return { jsFilePath: jsFilePath, sourceMapFilePath: sourceMapFilePath, declarationFilePath: declarationFilePath, declarationMapPath: declarationMapPath, buildInfoPath: undefined };
         }
@@ -91688,7 +91707,7 @@ var ts;
     }
     /* @internal */
     function getOutputDeclarationFileName(inputFileName, configFile, ignoreCase) {
-        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */));
+        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(inputFileName, ".json" /* Json */));
         return ts.changeExtension(getOutputPathWithoutChangingExt(inputFileName, configFile, ignoreCase, configFile.options.declarationDir || configFile.options.outDir), ".d.ts" /* Dts */);
     }
     ts.getOutputDeclarationFileName = getOutputDeclarationFileName;
@@ -91918,12 +91937,13 @@ var ts;
                 return;
             }
             var sourceFiles = ts.isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;
+            var filesForEmit = forceDtsEmit ? sourceFiles : ts.filter(sourceFiles, ts.isSourceFileNotJson);
             // Setup and perform the transformation to retrieve declarations from the input files
-            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(sourceFiles, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : sourceFiles;
+            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(filesForEmit, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : filesForEmit;
             if (emitOnlyDtsFiles && !ts.getEmitDeclarations(compilerOptions)) {
                 // Checker wont collect the linked aliases since thats only done when declaration is enabled.
                 // Do that here when emitting only dts files
-                sourceFiles.forEach(collectLinkedAliases);
+                filesForEmit.forEach(collectLinkedAliases);
             }
             var declarationTransform = ts.transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, /*allowDtsFiles*/ false);
             if (ts.length(declarationTransform.diagnostics)) {
@@ -97210,7 +97230,7 @@ var ts;
                             else if (ts.getEmitModuleKind(parsedRef.commandLine.options) === ts.ModuleKind.None) {
                                 for (var _c = 0, _d = parsedRef.commandLine.fileNames; _c < _d.length; _c++) {
                                     var fileName = _d[_c];
-                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                         processSourceFile(ts.getOutputDeclarationFileName(fileName, parsedRef.commandLine, !host.useCaseSensitiveFileNames()), /*isDefaultLib*/ false, /*ignoreNoDefaultLib*/ false, /*packageId*/ undefined);
                                     }
                                 }
@@ -98635,8 +98655,8 @@ var ts;
             return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
         }
         function getProjectReferenceRedirectProject(fileName) {
-            // Ignore dts
-            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+            // Ignore dts or any json files
+            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) || ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                 return undefined;
             }
             // If this file is produced by a referenced project, we need to rewrite it to
@@ -98690,7 +98710,7 @@ var ts;
                         }
                         else {
                             ts.forEach(resolvedRef.commandLine.fileNames, function (fileName) {
-                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                     var outputDts = ts.getOutputDeclarationFileName(fileName, resolvedRef.commandLine, host.useCaseSensitiveFileNames());
                                     mapFromToProjectReferenceRedirectSource.set(toPath(outputDts), fileName);
                                 }
@@ -110576,7 +110596,7 @@ var ts;
                 switch (contextToken.kind) {
                     case 27 /* CommaToken */:
                         return containingNodeKind === 242 /* VariableDeclaration */ ||
-                            containingNodeKind === 243 /* VariableDeclarationList */ ||
+                            isVariableDeclarationListButNotTypeArgument(contextToken) ||
                             containingNodeKind === 225 /* VariableStatement */ ||
                             containingNodeKind === 248 /* EnumDeclaration */ || // enum a { foo, |
                             isFunctionLikeButNotConstructor(containingNodeKind) ||
@@ -110687,6 +110707,10 @@ var ts;
                 }
                 return false;
             }
+            function isVariableDeclarationListButNotTypeArgument(node) {
+                return node.parent.kind === 243 /* VariableDeclarationList */
+                    && !ts.isPossiblyTypeArgumentPosition(node, sourceFile, typeChecker);
+            }
             /**
              * Filters out completion suggestions for named imports or exports.
              *
diff --git a/lib/typescriptServices.js b/lib/typescriptServices.js
index c63e7e84786..b01b3510b39 100644
--- a/lib/typescriptServices.js
+++ b/lib/typescriptServices.js
@@ -229,8 +229,8 @@ var ts;
 })(ts || (ts = {}));
 var ts;
 (function (ts) {
-    // WARNING: The script `configureNightly.ts` uses a regexp to parse out these values.
-    // If changing the text in this section, be sure to test `configureNightly` too.
+    // WARNING: The script `configurePrerelease.ts` uses a regexp to parse out these values.
+    // If changing the text in this section, be sure to test `configurePrerelease` too.
     ts.versionMajorMinor = "3.8";
     /** The version of the TypeScript compiler release */
     ts.version = ts.versionMajorMinor + ".0-beta";
@@ -7331,6 +7331,7 @@ var ts;
         The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access: diag(2779, ts.DiagnosticCategory.Error, "The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access_2779", "The left-hand side of an assignment expression may not be an optional property access."),
         The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access: diag(2780, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access_2780", "The left-hand side of a 'for...in' statement may not be an optional property access."),
         The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access: diag(2781, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access_2781", "The left-hand side of a 'for...of' statement may not be an optional property access."),
+        _0_needs_an_explicit_type_annotation: diag(2782, ts.DiagnosticCategory.Message, "_0_needs_an_explicit_type_annotation_2782", "'{0}' needs an explicit type annotation."),
         Import_declaration_0_is_using_private_name_1: diag(4000, ts.DiagnosticCategory.Error, "Import_declaration_0_is_using_private_name_1_4000", "Import declaration '{0}' is using private name '{1}'."),
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: diag(4002, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_class_has_or_is_using_private_name_1_4002", "Type parameter '{0}' of exported class has or is using private name '{1}'."),
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: diag(4004, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1_4004", "Type parameter '{0}' of exported interface has or is using private name '{1}'."),
@@ -14232,6 +14233,10 @@ var ts;
         return !!node && !!(node.flags & 33554432 /* JsonFile */);
     }
     ts.isInJsonFile = isInJsonFile;
+    function isSourceFileNotJson(file) {
+        return !isJsonSourceFile(file);
+    }
+    ts.isSourceFileNotJson = isSourceFileNotJson;
     function isInJSDoc(node) {
         return !!node && !!(node.flags & 4194304 /* JSDoc */);
     }
@@ -22394,10 +22399,12 @@ var ts;
             var propertyAccess = createNode(194 /* PropertyAccessExpression */, expression.pos);
             propertyAccess.expression = expression;
             propertyAccess.questionDotToken = questionDotToken;
-            // checker will error on private identifiers in optional chains, so don't have to catch them here
             propertyAccess.name = parseRightSideOfDot(/*allowIdentifierNames*/ true, /*allowPrivateIdentifiers*/ true);
             if (questionDotToken || expression.flags & 32 /* OptionalChain */) {
                 propertyAccess.flags |= 32 /* OptionalChain */;
+                if (ts.isPrivateIdentifier(propertyAccess.name)) {
+                    parseErrorAtRange(propertyAccess.name, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
+                }
             }
             return finishNode(propertyAccess);
         }
@@ -31448,7 +31455,7 @@ var ts;
                 ElementKind[ElementKind["Property"] = 1] = "Property";
                 ElementKind[ElementKind["Accessor"] = 2] = "Accessor";
             })(ElementKind || (ElementKind = {}));
-            if (inStrictMode) {
+            if (inStrictMode && !ts.isAssignmentTarget(node)) {
                 var seen = ts.createUnderscoreEscapedMap();
                 for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
                     var prop = _a[_i];
@@ -37853,6 +37860,9 @@ var ts;
                 /*decorators*/ undefined, indexInfo.isReadonly ? [ts.createToken(138 /* ReadonlyKeyword */)] : undefined, [indexingParameter], typeNode);
             }
             function signatureToSignatureDeclarationHelper(signature, kind, context) {
+                var suppressAny = context.flags & 256 /* SuppressAnyReturnType */;
+                if (suppressAny)
+                    context.flags &= ~256 /* SuppressAnyReturnType */; // suppress only toplevel `any`s
                 var typeParameters;
                 var typeArguments;
                 if (context.flags & 32 /* WriteTypeArgumentsOfSignature */ && signature.target && signature.mapper && signature.target.typeParameters) {
@@ -37880,15 +37890,12 @@ var ts;
                 }
                 else {
                     var returnType = getReturnTypeOfSignature(signature);
-                    returnTypeNode = returnType && typeToTypeNodeHelper(returnType, context);
-                }
-                if (context.flags & 256 /* SuppressAnyReturnType */) {
-                    if (returnTypeNode && returnTypeNode.kind === 125 /* AnyKeyword */) {
-                        returnTypeNode = undefined;
+                    if (returnType && !(suppressAny && isTypeAny(returnType))) {
+                        returnTypeNode = typeToTypeNodeHelper(returnType, context);
+                    }
+                    else if (!suppressAny) {
+                        returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                     }
-                }
-                else if (!returnTypeNode) {
-                    returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                 }
                 context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum
                 return ts.createSignatureDeclaration(kind, typeParameters, parameters, returnTypeNode, typeArguments);
@@ -46862,7 +46869,8 @@ var ts;
             return false;
         }
         function isEmptyResolvedType(t) {
-            return t.properties.length === 0 &&
+            return t !== anyFunctionType &&
+                t.properties.length === 0 &&
                 t.callSignatures.length === 0 &&
                 t.constructSignatures.length === 0 &&
                 !t.stringIndexInfo &&
@@ -51266,7 +51274,7 @@ var ts;
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }
@@ -51967,13 +51975,22 @@ var ts;
                 return type;
             }
             function narrowTypeByOptionalChainContainment(type, operator, value, assumeTrue) {
-                // We are in a branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
-                // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
-                // operator is !== and the type of value is undefined.
-                var effectiveTrue = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */ ? assumeTrue : !assumeTrue;
-                var doubleEquals = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */;
-                var valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? 262144 /* EQUndefinedOrNull */ : 65536 /* EQUndefined */));
-                return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
+                // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows:
+                // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch.
+                var equalsOperator = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */;
+                var nullableFlags = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */ ? 98304 /* Nullable */ : 32768 /* Undefined */;
+                var valueType = getTypeOfExpression(value);
+                // Note that we include any and unknown in the exclusion test because their domain includes null and undefined.
+                var removeNullable = equalsOperator !== assumeTrue && everyType(valueType, function (t) { return !!(t.flags & nullableFlags); }) ||
+                    equalsOperator === assumeTrue && everyType(valueType, function (t) { return !(t.flags & (3 /* AnyOrUnknown */ | nullableFlags)); });
+                return removeNullable ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
             }
             function narrowTypeByEquality(type, operator, value, assumeTrue) {
                 if (type.flags & 1 /* Any */) {
@@ -55103,10 +55120,6 @@ var ts;
             var assignmentKind = ts.getAssignmentTargetKind(node);
             var apparentType = getApparentType(assignmentKind !== 0 /* None */ || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType);
             if (ts.isPrivateIdentifier(right)) {
-                if (ts.isOptionalChain(node)) {
-                    grammarErrorOnNode(right, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
-                    return anyType;
-                }
                 checkExternalEmitHelpers(node, 262144 /* ClassPrivateFieldGet */);
             }
             var isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType;
@@ -63351,7 +63364,7 @@ var ts;
                 }
                 if (isInstancePropertyWithoutInitializer(member)) {
                     var propName = member.name;
-                    if (ts.isIdentifier(propName)) {
+                    if (ts.isIdentifier(propName) || ts.isPrivateIdentifier(propName)) {
                         var type = getTypeOfSymbol(getSymbolOfNode(member));
                         if (!(type.flags & 3 /* AnyOrUnknown */ || getFalsyFlags(type) & 32768 /* Undefined */)) {
                             if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) {
@@ -66588,28 +66601,30 @@ var ts;
                     default:
                         throw ts.Debug.assertNever(prop, "Unexpected syntax kind:" + prop.kind);
                 }
-                var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
-                if (effectiveName === undefined) {
-                    continue;
-                }
-                var existingKind = seen.get(effectiveName);
-                if (!existingKind) {
-                    seen.set(effectiveName, currentKind);
-                }
-                else {
-                    if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
-                        grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                if (!inDestructuring) {
+                    var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
+                    if (effectiveName === undefined) {
+                        continue;
                     }
-                    else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
-                        if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
-                            seen.set(effectiveName, currentKind | existingKind);
-                        }
-                        else {
-                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
-                        }
+                    var existingKind = seen.get(effectiveName);
+                    if (!existingKind) {
+                        seen.set(effectiveName, currentKind);
                     }
                     else {
-                        return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
+                            grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                        }
+                        else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
+                            if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
+                                seen.set(effectiveName, currentKind | existingKind);
+                            }
+                            else {
+                                return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
+                            }
+                        }
+                        else {
+                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        }
                     }
                 }
             }
@@ -89865,8 +89880,11 @@ var ts;
 var ts;
 (function (ts) {
     function getDeclarationDiagnostics(host, resolver, file) {
+        if (file && ts.isJsonSourceFile(file)) {
+            return []; // No declaration diagnostics for json for now
+        }
         var compilerOptions = host.getCompilerOptions();
-        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : host.getSourceFiles(), [transformDeclarations], /*allowDtsFiles*/ false);
+        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : ts.filter(host.getSourceFiles(), ts.isSourceFileNotJson), [transformDeclarations], /*allowDtsFiles*/ false);
         return result.diagnostics;
     }
     ts.getDeclarationDiagnostics = getDeclarationDiagnostics;
@@ -91642,12 +91660,13 @@ var ts;
         }
         else {
             var ownOutputFilePath = ts.getOwnEmitOutputFilePath(sourceFile.fileName, host, getOutputExtension(sourceFile, options));
+            var isJsonFile = ts.isJsonSourceFile(sourceFile);
             // If json file emits to the same location skip writing it, if emitDeclarationOnly skip writing it
-            var isJsonEmittedToSameLocation = ts.isJsonSourceFile(sourceFile) &&
+            var isJsonEmittedToSameLocation = isJsonFile &&
                 ts.comparePaths(sourceFile.fileName, ownOutputFilePath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === 0 /* EqualTo */;
             var jsFilePath = options.emitDeclarationOnly || isJsonEmittedToSameLocation ? undefined : ownOutputFilePath;
             var sourceMapFilePath = !jsFilePath || ts.isJsonSourceFile(sourceFile) ? undefined : getSourceMapFilePath(jsFilePath, options);
-            var declarationFilePath = (forceDtsPaths || ts.getEmitDeclarations(options)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
+            var declarationFilePath = (forceDtsPaths || (ts.getEmitDeclarations(options) && !isJsonFile)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
             var declarationMapPath = declarationFilePath && ts.getAreDeclarationMapsEnabled(options) ? declarationFilePath + ".map" : undefined;
             return { jsFilePath: jsFilePath, sourceMapFilePath: sourceMapFilePath, declarationFilePath: declarationFilePath, declarationMapPath: declarationMapPath, buildInfoPath: undefined };
         }
@@ -91688,7 +91707,7 @@ var ts;
     }
     /* @internal */
     function getOutputDeclarationFileName(inputFileName, configFile, ignoreCase) {
-        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */));
+        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(inputFileName, ".json" /* Json */));
         return ts.changeExtension(getOutputPathWithoutChangingExt(inputFileName, configFile, ignoreCase, configFile.options.declarationDir || configFile.options.outDir), ".d.ts" /* Dts */);
     }
     ts.getOutputDeclarationFileName = getOutputDeclarationFileName;
@@ -91918,12 +91937,13 @@ var ts;
                 return;
             }
             var sourceFiles = ts.isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;
+            var filesForEmit = forceDtsEmit ? sourceFiles : ts.filter(sourceFiles, ts.isSourceFileNotJson);
             // Setup and perform the transformation to retrieve declarations from the input files
-            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(sourceFiles, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : sourceFiles;
+            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(filesForEmit, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : filesForEmit;
             if (emitOnlyDtsFiles && !ts.getEmitDeclarations(compilerOptions)) {
                 // Checker wont collect the linked aliases since thats only done when declaration is enabled.
                 // Do that here when emitting only dts files
-                sourceFiles.forEach(collectLinkedAliases);
+                filesForEmit.forEach(collectLinkedAliases);
             }
             var declarationTransform = ts.transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, /*allowDtsFiles*/ false);
             if (ts.length(declarationTransform.diagnostics)) {
@@ -97210,7 +97230,7 @@ var ts;
                             else if (ts.getEmitModuleKind(parsedRef.commandLine.options) === ts.ModuleKind.None) {
                                 for (var _c = 0, _d = parsedRef.commandLine.fileNames; _c < _d.length; _c++) {
                                     var fileName = _d[_c];
-                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                         processSourceFile(ts.getOutputDeclarationFileName(fileName, parsedRef.commandLine, !host.useCaseSensitiveFileNames()), /*isDefaultLib*/ false, /*ignoreNoDefaultLib*/ false, /*packageId*/ undefined);
                                     }
                                 }
@@ -98635,8 +98655,8 @@ var ts;
             return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
         }
         function getProjectReferenceRedirectProject(fileName) {
-            // Ignore dts
-            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+            // Ignore dts or any json files
+            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) || ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                 return undefined;
             }
             // If this file is produced by a referenced project, we need to rewrite it to
@@ -98690,7 +98710,7 @@ var ts;
                         }
                         else {
                             ts.forEach(resolvedRef.commandLine.fileNames, function (fileName) {
-                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                     var outputDts = ts.getOutputDeclarationFileName(fileName, resolvedRef.commandLine, host.useCaseSensitiveFileNames());
                                     mapFromToProjectReferenceRedirectSource.set(toPath(outputDts), fileName);
                                 }
@@ -110576,7 +110596,7 @@ var ts;
                 switch (contextToken.kind) {
                     case 27 /* CommaToken */:
                         return containingNodeKind === 242 /* VariableDeclaration */ ||
-                            containingNodeKind === 243 /* VariableDeclarationList */ ||
+                            isVariableDeclarationListButNotTypeArgument(contextToken) ||
                             containingNodeKind === 225 /* VariableStatement */ ||
                             containingNodeKind === 248 /* EnumDeclaration */ || // enum a { foo, |
                             isFunctionLikeButNotConstructor(containingNodeKind) ||
@@ -110687,6 +110707,10 @@ var ts;
                 }
                 return false;
             }
+            function isVariableDeclarationListButNotTypeArgument(node) {
+                return node.parent.kind === 243 /* VariableDeclarationList */
+                    && !ts.isPossiblyTypeArgumentPosition(node, sourceFile, typeChecker);
+            }
             /**
              * Filters out completion suggestions for named imports or exports.
              *
diff --git a/lib/typingsInstaller.js b/lib/typingsInstaller.js
index ec86a833529..e4aadbe0bc8 100644
--- a/lib/typingsInstaller.js
+++ b/lib/typingsInstaller.js
@@ -79,8 +79,8 @@ var __extends = (this && this.__extends) || (function () {
 })();
 var ts;
 (function (ts) {
-    // WARNING: The script `configureNightly.ts` uses a regexp to parse out these values.
-    // If changing the text in this section, be sure to test `configureNightly` too.
+    // WARNING: The script `configurePrerelease.ts` uses a regexp to parse out these values.
+    // If changing the text in this section, be sure to test `configurePrerelease` too.
     ts.versionMajorMinor = "3.8";
     /** The version of the TypeScript compiler release */
     ts.version = ts.versionMajorMinor + ".0-beta";
@@ -7181,6 +7181,7 @@ var ts;
         The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access: diag(2779, ts.DiagnosticCategory.Error, "The_left_hand_side_of_an_assignment_expression_may_not_be_an_optional_property_access_2779", "The left-hand side of an assignment expression may not be an optional property access."),
         The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access: diag(2780, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_in_statement_may_not_be_an_optional_property_access_2780", "The left-hand side of a 'for...in' statement may not be an optional property access."),
         The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access: diag(2781, ts.DiagnosticCategory.Error, "The_left_hand_side_of_a_for_of_statement_may_not_be_an_optional_property_access_2781", "The left-hand side of a 'for...of' statement may not be an optional property access."),
+        _0_needs_an_explicit_type_annotation: diag(2782, ts.DiagnosticCategory.Message, "_0_needs_an_explicit_type_annotation_2782", "'{0}' needs an explicit type annotation."),
         Import_declaration_0_is_using_private_name_1: diag(4000, ts.DiagnosticCategory.Error, "Import_declaration_0_is_using_private_name_1_4000", "Import declaration '{0}' is using private name '{1}'."),
         Type_parameter_0_of_exported_class_has_or_is_using_private_name_1: diag(4002, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_class_has_or_is_using_private_name_1_4002", "Type parameter '{0}' of exported class has or is using private name '{1}'."),
         Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1: diag(4004, ts.DiagnosticCategory.Error, "Type_parameter_0_of_exported_interface_has_or_is_using_private_name_1_4004", "Type parameter '{0}' of exported interface has or is using private name '{1}'."),
@@ -14082,6 +14083,10 @@ var ts;
         return !!node && !!(node.flags & 33554432 /* JsonFile */);
     }
     ts.isInJsonFile = isInJsonFile;
+    function isSourceFileNotJson(file) {
+        return !isJsonSourceFile(file);
+    }
+    ts.isSourceFileNotJson = isSourceFileNotJson;
     function isInJSDoc(node) {
         return !!node && !!(node.flags & 4194304 /* JSDoc */);
     }
@@ -22244,10 +22249,12 @@ var ts;
             var propertyAccess = createNode(194 /* PropertyAccessExpression */, expression.pos);
             propertyAccess.expression = expression;
             propertyAccess.questionDotToken = questionDotToken;
-            // checker will error on private identifiers in optional chains, so don't have to catch them here
             propertyAccess.name = parseRightSideOfDot(/*allowIdentifierNames*/ true, /*allowPrivateIdentifiers*/ true);
             if (questionDotToken || expression.flags & 32 /* OptionalChain */) {
                 propertyAccess.flags |= 32 /* OptionalChain */;
+                if (ts.isPrivateIdentifier(propertyAccess.name)) {
+                    parseErrorAtRange(propertyAccess.name, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
+                }
             }
             return finishNode(propertyAccess);
         }
@@ -31298,7 +31305,7 @@ var ts;
                 ElementKind[ElementKind["Property"] = 1] = "Property";
                 ElementKind[ElementKind["Accessor"] = 2] = "Accessor";
             })(ElementKind || (ElementKind = {}));
-            if (inStrictMode) {
+            if (inStrictMode && !ts.isAssignmentTarget(node)) {
                 var seen = ts.createUnderscoreEscapedMap();
                 for (var _i = 0, _a = node.properties; _i < _a.length; _i++) {
                     var prop = _a[_i];
@@ -37703,6 +37710,9 @@ var ts;
                 /*decorators*/ undefined, indexInfo.isReadonly ? [ts.createToken(138 /* ReadonlyKeyword */)] : undefined, [indexingParameter], typeNode);
             }
             function signatureToSignatureDeclarationHelper(signature, kind, context) {
+                var suppressAny = context.flags & 256 /* SuppressAnyReturnType */;
+                if (suppressAny)
+                    context.flags &= ~256 /* SuppressAnyReturnType */; // suppress only toplevel `any`s
                 var typeParameters;
                 var typeArguments;
                 if (context.flags & 32 /* WriteTypeArgumentsOfSignature */ && signature.target && signature.mapper && signature.target.typeParameters) {
@@ -37730,15 +37740,12 @@ var ts;
                 }
                 else {
                     var returnType = getReturnTypeOfSignature(signature);
-                    returnTypeNode = returnType && typeToTypeNodeHelper(returnType, context);
-                }
-                if (context.flags & 256 /* SuppressAnyReturnType */) {
-                    if (returnTypeNode && returnTypeNode.kind === 125 /* AnyKeyword */) {
-                        returnTypeNode = undefined;
+                    if (returnType && !(suppressAny && isTypeAny(returnType))) {
+                        returnTypeNode = typeToTypeNodeHelper(returnType, context);
+                    }
+                    else if (!suppressAny) {
+                        returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                     }
-                }
-                else if (!returnTypeNode) {
-                    returnTypeNode = ts.createKeywordTypeNode(125 /* AnyKeyword */);
                 }
                 context.approximateLength += 3; // Usually a signature contributes a few more characters than this, but 3 is the minimum
                 return ts.createSignatureDeclaration(kind, typeParameters, parameters, returnTypeNode, typeArguments);
@@ -46712,7 +46719,8 @@ var ts;
             return false;
         }
         function isEmptyResolvedType(t) {
-            return t.properties.length === 0 &&
+            return t !== anyFunctionType &&
+                t.properties.length === 0 &&
                 t.callSignatures.length === 0 &&
                 t.constructSignatures.length === 0 &&
                 !t.stringIndexInfo &&
@@ -51116,7 +51124,7 @@ var ts;
                     return getTypeOfSymbol(symbol);
                 }
                 if (diagnostic && symbol.valueDeclaration) {
-                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_is_declared_here, symbolToString(symbol)));
+                    ts.addRelatedInfo(diagnostic, ts.createDiagnosticForNode(symbol.valueDeclaration, ts.Diagnostics._0_needs_an_explicit_type_annotation, symbolToString(symbol)));
                 }
             }
         }
@@ -51817,13 +51825,22 @@ var ts;
                 return type;
             }
             function narrowTypeByOptionalChainContainment(type, operator, value, assumeTrue) {
-                // We are in a branch of obj?.foo === value or obj?.foo !== value. We remove undefined and null from
-                // the type of obj if (a) the operator is === and the type of value doesn't include undefined or (b) the
-                // operator is !== and the type of value is undefined.
-                var effectiveTrue = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */ ? assumeTrue : !assumeTrue;
-                var doubleEquals = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */;
-                var valueNonNullish = !(getTypeFacts(getTypeOfExpression(value)) & (doubleEquals ? 262144 /* EQUndefinedOrNull */ : 65536 /* EQUndefined */));
-                return effectiveTrue === valueNonNullish ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
+                // We are in a branch of obj?.foo === value (or any one of the other equality operators). We narrow obj as follows:
+                // When operator is === and type of value excludes undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is !== and type of value excludes undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is == and type of value excludes null and undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is != and type of value excludes null and undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is === and type of value is undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is !== and type of value is undefined, null and undefined is removed from type of obj in true branch.
+                // When operator is == and type of value is null or undefined, null and undefined is removed from type of obj in false branch.
+                // When operator is != and type of value is null or undefined, null and undefined is removed from type of obj in true branch.
+                var equalsOperator = operator === 34 /* EqualsEqualsToken */ || operator === 36 /* EqualsEqualsEqualsToken */;
+                var nullableFlags = operator === 34 /* EqualsEqualsToken */ || operator === 35 /* ExclamationEqualsToken */ ? 98304 /* Nullable */ : 32768 /* Undefined */;
+                var valueType = getTypeOfExpression(value);
+                // Note that we include any and unknown in the exclusion test because their domain includes null and undefined.
+                var removeNullable = equalsOperator !== assumeTrue && everyType(valueType, function (t) { return !!(t.flags & nullableFlags); }) ||
+                    equalsOperator === assumeTrue && everyType(valueType, function (t) { return !(t.flags & (3 /* AnyOrUnknown */ | nullableFlags)); });
+                return removeNullable ? getTypeWithFacts(type, 2097152 /* NEUndefinedOrNull */) : type;
             }
             function narrowTypeByEquality(type, operator, value, assumeTrue) {
                 if (type.flags & 1 /* Any */) {
@@ -54953,10 +54970,6 @@ var ts;
             var assignmentKind = ts.getAssignmentTargetKind(node);
             var apparentType = getApparentType(assignmentKind !== 0 /* None */ || isMethodAccessForCall(node) ? getWidenedType(leftType) : leftType);
             if (ts.isPrivateIdentifier(right)) {
-                if (ts.isOptionalChain(node)) {
-                    grammarErrorOnNode(right, ts.Diagnostics.An_optional_chain_cannot_contain_private_identifiers);
-                    return anyType;
-                }
                 checkExternalEmitHelpers(node, 262144 /* ClassPrivateFieldGet */);
             }
             var isAnyLike = isTypeAny(apparentType) || apparentType === silentNeverType;
@@ -63201,7 +63214,7 @@ var ts;
                 }
                 if (isInstancePropertyWithoutInitializer(member)) {
                     var propName = member.name;
-                    if (ts.isIdentifier(propName)) {
+                    if (ts.isIdentifier(propName) || ts.isPrivateIdentifier(propName)) {
                         var type = getTypeOfSymbol(getSymbolOfNode(member));
                         if (!(type.flags & 3 /* AnyOrUnknown */ || getFalsyFlags(type) & 32768 /* Undefined */)) {
                             if (!constructor || !isPropertyInitializedInConstructor(propName, type, constructor)) {
@@ -66438,28 +66451,30 @@ var ts;
                     default:
                         throw ts.Debug.assertNever(prop, "Unexpected syntax kind:" + prop.kind);
                 }
-                var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
-                if (effectiveName === undefined) {
-                    continue;
-                }
-                var existingKind = seen.get(effectiveName);
-                if (!existingKind) {
-                    seen.set(effectiveName, currentKind);
-                }
-                else {
-                    if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
-                        grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                if (!inDestructuring) {
+                    var effectiveName = ts.getPropertyNameForPropertyNameNode(name);
+                    if (effectiveName === undefined) {
+                        continue;
                     }
-                    else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
-                        if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
-                            seen.set(effectiveName, currentKind | existingKind);
-                        }
-                        else {
-                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
-                        }
+                    var existingKind = seen.get(effectiveName);
+                    if (!existingKind) {
+                        seen.set(effectiveName, currentKind);
                     }
                     else {
-                        return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        if ((currentKind & 12 /* PropertyAssignmentOrMethod */) && (existingKind & 12 /* PropertyAssignmentOrMethod */)) {
+                            grammarErrorOnNode(name, ts.Diagnostics.Duplicate_identifier_0, ts.getTextOfNode(name));
+                        }
+                        else if ((currentKind & 3 /* GetOrSetAccessor */) && (existingKind & 3 /* GetOrSetAccessor */)) {
+                            if (existingKind !== 3 /* GetOrSetAccessor */ && currentKind !== existingKind) {
+                                seen.set(effectiveName, currentKind | existingKind);
+                            }
+                            else {
+                                return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_multiple_get_Slashset_accessors_with_the_same_name);
+                            }
+                        }
+                        else {
+                            return grammarErrorOnNode(name, ts.Diagnostics.An_object_literal_cannot_have_property_and_accessor_with_the_same_name);
+                        }
                     }
                 }
             }
@@ -89715,8 +89730,11 @@ var ts;
 var ts;
 (function (ts) {
     function getDeclarationDiagnostics(host, resolver, file) {
+        if (file && ts.isJsonSourceFile(file)) {
+            return []; // No declaration diagnostics for json for now
+        }
         var compilerOptions = host.getCompilerOptions();
-        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : host.getSourceFiles(), [transformDeclarations], /*allowDtsFiles*/ false);
+        var result = ts.transformNodes(resolver, host, compilerOptions, file ? [file] : ts.filter(host.getSourceFiles(), ts.isSourceFileNotJson), [transformDeclarations], /*allowDtsFiles*/ false);
         return result.diagnostics;
     }
     ts.getDeclarationDiagnostics = getDeclarationDiagnostics;
@@ -91492,12 +91510,13 @@ var ts;
         }
         else {
             var ownOutputFilePath = ts.getOwnEmitOutputFilePath(sourceFile.fileName, host, getOutputExtension(sourceFile, options));
+            var isJsonFile = ts.isJsonSourceFile(sourceFile);
             // If json file emits to the same location skip writing it, if emitDeclarationOnly skip writing it
-            var isJsonEmittedToSameLocation = ts.isJsonSourceFile(sourceFile) &&
+            var isJsonEmittedToSameLocation = isJsonFile &&
                 ts.comparePaths(sourceFile.fileName, ownOutputFilePath, host.getCurrentDirectory(), !host.useCaseSensitiveFileNames()) === 0 /* EqualTo */;
             var jsFilePath = options.emitDeclarationOnly || isJsonEmittedToSameLocation ? undefined : ownOutputFilePath;
             var sourceMapFilePath = !jsFilePath || ts.isJsonSourceFile(sourceFile) ? undefined : getSourceMapFilePath(jsFilePath, options);
-            var declarationFilePath = (forceDtsPaths || ts.getEmitDeclarations(options)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
+            var declarationFilePath = (forceDtsPaths || (ts.getEmitDeclarations(options) && !isJsonFile)) ? ts.getDeclarationEmitOutputFilePath(sourceFile.fileName, host) : undefined;
             var declarationMapPath = declarationFilePath && ts.getAreDeclarationMapsEnabled(options) ? declarationFilePath + ".map" : undefined;
             return { jsFilePath: jsFilePath, sourceMapFilePath: sourceMapFilePath, declarationFilePath: declarationFilePath, declarationMapPath: declarationMapPath, buildInfoPath: undefined };
         }
@@ -91538,7 +91557,7 @@ var ts;
     }
     /* @internal */
     function getOutputDeclarationFileName(inputFileName, configFile, ignoreCase) {
-        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */));
+        ts.Debug.assert(!ts.fileExtensionIs(inputFileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(inputFileName, ".json" /* Json */));
         return ts.changeExtension(getOutputPathWithoutChangingExt(inputFileName, configFile, ignoreCase, configFile.options.declarationDir || configFile.options.outDir), ".d.ts" /* Dts */);
     }
     ts.getOutputDeclarationFileName = getOutputDeclarationFileName;
@@ -91768,12 +91787,13 @@ var ts;
                 return;
             }
             var sourceFiles = ts.isSourceFile(sourceFileOrBundle) ? [sourceFileOrBundle] : sourceFileOrBundle.sourceFiles;
+            var filesForEmit = forceDtsEmit ? sourceFiles : ts.filter(sourceFiles, ts.isSourceFileNotJson);
             // Setup and perform the transformation to retrieve declarations from the input files
-            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(sourceFiles, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : sourceFiles;
+            var inputListOrBundle = (compilerOptions.outFile || compilerOptions.out) ? [ts.createBundle(filesForEmit, !ts.isSourceFile(sourceFileOrBundle) ? sourceFileOrBundle.prepends : undefined)] : filesForEmit;
             if (emitOnlyDtsFiles && !ts.getEmitDeclarations(compilerOptions)) {
                 // Checker wont collect the linked aliases since thats only done when declaration is enabled.
                 // Do that here when emitting only dts files
-                sourceFiles.forEach(collectLinkedAliases);
+                filesForEmit.forEach(collectLinkedAliases);
             }
             var declarationTransform = ts.transformNodes(resolver, host, compilerOptions, inputListOrBundle, declarationTransformers, /*allowDtsFiles*/ false);
             if (ts.length(declarationTransform.diagnostics)) {
@@ -97060,7 +97080,7 @@ var ts;
                             else if (ts.getEmitModuleKind(parsedRef.commandLine.options) === ts.ModuleKind.None) {
                                 for (var _c = 0, _d = parsedRef.commandLine.fileNames; _c < _d.length; _c++) {
                                     var fileName = _d[_c];
-                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                    if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                         processSourceFile(ts.getOutputDeclarationFileName(fileName, parsedRef.commandLine, !host.useCaseSensitiveFileNames()), /*isDefaultLib*/ false, /*ignoreNoDefaultLib*/ false, /*packageId*/ undefined);
                                     }
                                 }
@@ -98485,8 +98505,8 @@ var ts;
             return referencedProject && getProjectReferenceOutputName(referencedProject, fileName);
         }
         function getProjectReferenceRedirectProject(fileName) {
-            // Ignore dts
-            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+            // Ignore dts or any json files
+            if (!resolvedProjectReferences || !resolvedProjectReferences.length || ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) || ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                 return undefined;
             }
             // If this file is produced by a referenced project, we need to rewrite it to
@@ -98540,7 +98560,7 @@ var ts;
                         }
                         else {
                             ts.forEach(resolvedRef.commandLine.fileNames, function (fileName) {
-                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */)) {
+                                if (!ts.fileExtensionIs(fileName, ".d.ts" /* Dts */) && !ts.fileExtensionIs(fileName, ".json" /* Json */)) {
                                     var outputDts = ts.getOutputDeclarationFileName(fileName, resolvedRef.commandLine, host.useCaseSensitiveFileNames());
                                     mapFromToProjectReferenceRedirectSource.set(toPath(outputDts), fileName);
                                 }