title: ERROR in TypeError: Cannot read property 'flags' of undefined
body: <p>I have a problem when I try to run <code>ng serve</code> on a recently created Angular project.
  The version I'm using is 9.1.4, this error does not occur on a project with an older Angular version.</p>
  
  <pre><code>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
  </code></pre>
  
  <p>After executing <code>ng serve</code> or <code>ng build</code>:</p>
  
  <pre><code>chunk {main} main.js, main.js.map (main) 2 kB [initial] [rendered]&lt;br&gt;
  chunk {polyfills} polyfills.js, polyfills.js.map (polyfills) 679 bytes [initial] [rendered]&lt;br&gt;
  chunk {runtime} runtime.js, runtime.js.map (runtime) 6.15 kB [entry] [rendered]&lt;br&gt;
  chunk {styles} styles.js, styles.js.map (styles) 12.4 kB [initial] [rendered]&lt;br&gt;
  chunk {vendor} vendor.js, vendor.js.map (vendor) 339 kB [initial] [rendered]&lt;br&gt;
  Date: 2020-05-08T02:06:46.145Z - Hash: 1a1b937f0ca2bb37634b - Time: 4087ms&lt;br&gt;
  
  **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/** **
  </code></pre>
  
  <p>The result I get on my browser after running this project is:</p>
  
  <pre><code>Cannot GET /
  </code></pre>