TypeErrorのエラー：未定義のプロパティ 'flags'を読み取れません

Question

最近作成したAngularプロジェクトでng serveを実行しようとすると問題が発生します。使用しているバージョンは9.1.4です。このエラーは、古いAngularバージョン。

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.901.4
@angular-devkit/build-angular     0.901.4
@angular-devkit/build-optimizer   0.901.4
@angular-devkit/build-webpack     0.901.4
@angular-devkit/core              9.1.4
@angular-devkit/schematics        9.1.4
@angular/cli                      9.1.4
@ngtools/webpack                  9.1.4
@schematics/angular               9.1.4
@schematics/update                0.901.4
rxjs                              6.5.5
TypeScript                        3.8.3
webpack                           4.42.0

ng serveまたはng buildを実行した後：

chunk {main} main.js, main.js.map (main) 2 kB [initial] [rendered]<br>
chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 679 bytes [initial] [rendered]<br>
chunk {runtime} runtime.js, runtime.js.map (runtime) 6.15 kB [entry] [rendered]<br>
chunk {styles} styles.js, styles.js.map (styles) 12.4 kB [initial] [rendered]<br>
chunk {vendor} vendor.js, vendor.js.map (vendor) 339 kB [initial] [rendered]<br>
Date: 2020-05-08T02:06:46.145Z - Hash: 1a1b937f0ca2bb37634b - Time: 4087ms<br>

**ERROR in TypeError: Cannot read property 'flags' of undefined**
    at resolveAlias (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:36513:37)
    at checkAliasSymbol (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:64502:26)
    at checkImportBinding (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:64534:13)
    at checkImportDeclaration (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:64552:29)
    at checkSourceElementWorker (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:64961:28)
    at checkSourceElement (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:64800:17)
    at Object.forEach (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:317:30)
    at checkSourceFileWorker (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:65123:20)
    at checkSourceFile (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:65091:13)
    at getDiagnosticsWorker (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:65179:17)
    at Object.getDiagnostics (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:65165:24)
    at C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:98703:85
    at runWithCancellationToken (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:98665:24)
    at getBindAndCheckDiagnosticsForFileNoCache (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:98691:20)
    at getAndCacheDiagnostics (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:98956:26)
    at getBindAndCheckDiagnosticsForFile (C:\Cursos\Angular\ang-hello-world\node_modules\TypeScript\lib\TypeScript.js:98688:20)

** **Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/** **

このプロジェクトを実行した後、ブラウザに表示される結果は次のとおりです。

Cannot GET /

Answer 1

この解決策を試してください：

npm install @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected] @angular/[email protected]

npm install

ng serve