bit more cleanup

src/compiler/emitter.ts

@@ -6794,6 +6794,9 @@ var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, Promi
                     specifier = (declaration as ImportDeclaration|ExportDeclaration).moduleSpecifier;
                 }
                 let moduleSymbol = resolver.getSymbolAtLocation(specifier);
+                if (!moduleSymbol) {
+                    return;    
+                }
                 let moduleDeclaration = getDeclarationOfKind(moduleSymbol, SyntaxKind.SourceFile) as SourceFile;
                 if (!moduleDeclaration || isDeclarationFile(moduleDeclaration)) {
                     return;