When emitting metadata about type, Use object type if the type cant be resolved

This could be true if expression cannot be resolved resulting in error

src/compiler/checker.ts

@@ -14409,6 +14409,10 @@ namespace ts {
 
             // Resolve the symbol as a type so that we can provide a more useful hint for the type serializer.
             let typeSymbol = resolveEntityName(typeName, SymbolFlags.Type, /*ignoreErrors*/ true);
+            // We might not be able to resolve type symbol so use unknown type in that case (eg error case)
+            if (!typeSymbol) {
+                return TypeReferenceSerializationKind.ObjectType; 
+            }
             let type = getDeclaredTypeOfSymbol(typeSymbol);
             if (type === unknownType) {
                 return TypeReferenceSerializationKind.Unknown;

tests/baselines/reference/decoratorMetadataWithImportDeclarationNameCollision4.errors.txt

@@ -0,0 +1,27 @@
+tests/cases/compiler/service.ts(1,8): error TS1192: Module '"tests/cases/compiler/db"' has no default export.
+
+
+==== tests/cases/compiler/db.ts (0 errors) ====
+    export class db {
+        public doSomething() {
+        }
+    }
+    
+==== tests/cases/compiler/service.ts (1 errors) ====
+    import db from './db'; // error no default export
+           ~~
+!!! error TS1192: Module '"tests/cases/compiler/db"' has no default export.
+    function someDecorator(target) {
+        return target;
+    }
+    @someDecorator
+    class MyClass {
+        db: db.db;
+    
+        constructor(db: db.db) {
+            this.db = db;
+            this.db.doSomething();
+        }
+    }
+    export {MyClass};
+    

tests/baselines/reference/decoratorMetadataWithImportDeclarationNameCollision4.js

@@ -0,0 +1,51 @@
+//// [tests/cases/compiler/decoratorMetadataWithImportDeclarationNameCollision4.ts] ////
+
+//// [db.ts]
+export class db {
+    public doSomething() {
+    }
+}
+
+//// [service.ts]
+import db from './db'; // error no default export
+function someDecorator(target) {
+    return target;
+}
+@someDecorator
+class MyClass {
+    db: db.db;
+
+    constructor(db: db.db) {
+        this.db = db;
+        this.db.doSomething();
+    }
+}
+export {MyClass};
+
+
+//// [db.js]
+var db = (function () {
+    function db() {
+    }
+    db.prototype.doSomething = function () {
+    };
+    return db;
+})();
+exports.db = db;
+//// [service.js]
+var db_1 = require('./db'); // error no default export
+function someDecorator(target) {
+    return target;
+}
+var MyClass = (function () {
+    function MyClass(db) {
+        this.db = db;
+        this.db.doSomething();
+    }
+    MyClass = __decorate([
+        someDecorator, 
+        __metadata('design:paramtypes', [Object])
+    ], MyClass);
+    return MyClass;
+})();
+exports.MyClass = MyClass;

tests/baselines/reference/decoratorMetadataWithImportDeclarationNameCollision7.errors.txt

@@ -0,0 +1,30 @@
+tests/cases/compiler/service.ts(7,9): error TS2503: Cannot find namespace 'db'.
+tests/cases/compiler/service.ts(9,21): error TS2503: Cannot find namespace 'db'.
+
+
+==== tests/cases/compiler/db.ts (0 errors) ====
+    export default class db {
+        public doSomething() {
+        }
+    }
+    
+==== tests/cases/compiler/service.ts (2 errors) ====
+    import db from './db';
+    function someDecorator(target) {
+        return target;
+    }
+    @someDecorator
+    class MyClass {
+        db: db.db; //error
+            ~~
+!!! error TS2503: Cannot find namespace 'db'.
+    
+        constructor(db: db.db) { // error
+                        ~~
+!!! error TS2503: Cannot find namespace 'db'.
+            this.db = db;
+            this.db.doSomething();
+        }
+    }
+    export {MyClass};
+    

tests/baselines/reference/decoratorMetadataWithImportDeclarationNameCollision7.js

@@ -0,0 +1,52 @@
+//// [tests/cases/compiler/decoratorMetadataWithImportDeclarationNameCollision7.ts] ////
+
+//// [db.ts]
+export default class db {
+    public doSomething() {
+    }
+}
+
+//// [service.ts]
+import db from './db';
+function someDecorator(target) {
+    return target;
+}
+@someDecorator
+class MyClass {
+    db: db.db; //error
+
+    constructor(db: db.db) { // error
+        this.db = db;
+        this.db.doSomething();
+    }
+}
+export {MyClass};
+
+
+//// [db.js]
+var db = (function () {
+    function db() {
+    }
+    db.prototype.doSomething = function () {
+    };
+    return db;
+})();
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.default = db;
+//// [service.js]
+var db_1 = require('./db');
+function someDecorator(target) {
+    return target;
+}
+var MyClass = (function () {
+    function MyClass(db) {
+        this.db = db;
+        this.db.doSomething();
+    }
+    MyClass = __decorate([
+        someDecorator, 
+        __metadata('design:paramtypes', [Object])
+    ], MyClass);
+    return MyClass;
+})();
+exports.MyClass = MyClass;

tests/cases/compiler/decoratorMetadataWithImportDeclarationNameCollision4.ts

@@ -0,0 +1,26 @@
+// @noemithelpers: true
+// @experimentaldecorators: true
+// @emitdecoratormetadata: true
+// @target: es5
+// @module: commonjs
+// @filename: db.ts
+export class db {
+    public doSomething() {
+    }
+}
+
+// @filename: service.ts
+import db from './db'; // error no default export
+function someDecorator(target) {
+    return target;
+}
+@someDecorator
+class MyClass {
+    db: db.db;
+
+    constructor(db: db.db) {
+        this.db = db;
+        this.db.doSomething();
+    }
+}
+export {MyClass};

tests/cases/compiler/decoratorMetadataWithImportDeclarationNameCollision7.ts

@@ -0,0 +1,26 @@
+// @noemithelpers: true
+// @experimentaldecorators: true
+// @emitdecoratormetadata: true
+// @target: es5
+// @module: commonjs
+// @filename: db.ts
+export default class db {
+    public doSomething() {
+    }
+}
+
+// @filename: service.ts
+import db from './db';
+function someDecorator(target) {
+    return target;
+}
+@someDecorator
+class MyClass {
+    db: db.db; //error
+
+    constructor(db: db.db) { // error
+        this.db = db;
+        this.db.doSomething();
+    }
+}
+export {MyClass};