title: How to debug the error that's generated while building with ng build --prod?
body: <p>I have created an app and wanted to build it using <code>ng build --prod</code>. While I did so, I got an error message with the current version of syncfusion.</p>
  
  <p>The following is the error I'm getting:</p>
  
  <pre><code>ERROR in ./node_modules/@syncfusion/ej2-angular-dropdowns/@syncfusion/ej2-angular-dropdowns.es5.js
  Module build failed (from ./node_modules/@angular-devkit/build-optimizer/src/build-optimizer/webpack-loader.js):
  Error: Debug Failure. False expression.
      at getJSDocTags (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13197:22)
      at getFirstJSDocTag (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13205:24)
      at Object.getJSDocTypeTag (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13154:19)
      at checkParenthesizedExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45628:56)
      at checkExpressionWorker (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45676:28)
      at checkExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45609:42)
      at checkBinaryLikeExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45155:29)
      at checkBinaryExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45147:20)
      at checkExpressionWorker (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45702:28)
      at checkExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45609:42)
      at checkExpressionCached (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45457:38)
      at getTypeOfExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45577:28)
      at checkDeclarationInitializer (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45469:24)
      at getTypeForVariableLikeDeclaration (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:30738:28)
      at getWidenedTypeForVariableLikeDeclaration (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:30961:24)
      at getTypeOfVariableOrParameterOrProperty (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:31062:28)
  ERROR in ./node_modules/@syncfusion/ej2-angular-calendars/@syncfusion/ej2-angular-calendars.es5.js
  Module build failed (from ./node_modules/@angular-devkit/build-optimizer/src/build-optimizer/webpack-loader.js):
  Error: Debug Failure. False expression.
      at getJSDocTags (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13197:22)
      at getFirstJSDocTag (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13205:24)
      at Object.getJSDocTypeTag (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13154:19)
      at checkParenthesizedExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45628:56)
      at checkExpressionWorker (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45676:28)
      at checkExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45609:42)
      at checkBinaryLikeExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45155:29)
      at checkBinaryExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45147:20)
      at checkExpressionWorker (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45702:28)
      at checkExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45609:42)
      at checkExpressionCached (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45457:38)
      at getTypeOfExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45577:28)
      at checkDeclarationInitializer (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45469:24)
      at getTypeForVariableLikeDeclaration (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:30738:28)
      at getWidenedTypeForVariableLikeDeclaration (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:30961:24)
      at getTypeOfVariableOrParameterOrProperty (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:31062:28)
  ERROR in ./node_modules/@syncfusion/ej2-angular-inputs/@syncfusion/ej2-angular-inputs.es5.js
  Module build failed (from ./node_modules/@angular-devkit/build-optimizer/src/build-optimizer/webpack-loader.js):
  Error: Debug Failure. False expression.
      at getJSDocTags (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13197:22)
      at getFirstJSDocTag (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13205:24)
      at Object.getJSDocTypeTag (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:13154:19)
      at checkParenthesizedExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45628:56)
      at checkExpressionWorker (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45676:28)
      at checkExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45609:42)
      at checkBinaryLikeExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45155:29)
      at checkBinaryExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45147:20)
      at checkExpressionWorker (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45702:28)
      at checkExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45609:42)
      at checkExpressionCached (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45457:38)
      at getTypeOfExpression (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45577:28)
      at checkDeclarationInitializer (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:45469:24)
      at getTypeForVariableLikeDeclaration (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:30738:28)
      at getWidenedTypeForVariableLikeDeclaration (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:30961:24)
      at getTypeOfVariableOrParameterOrProperty (F:\school-web-admin\node_modules\@angular-devkit\build-optimizer\node_modules\typescript\lib\typescript.js:31062:28)
  i ｢wdm｣: Failed to compile
  </code></pre>
  
  <p>.</p>
  
  <p>The following is the dependency used for Syncfusion:</p>
  
  <pre><code>"@syncfusion/ej2-angular-calendars": "^17.1.49",
  "@syncfusion/ej2-angular-dropdowns": "^17.1.49",
  "@syncfusion/ej2-angular-inputs": "^17.1.49",
  "@syncfusion/ej2-angular-splitbuttons": "^17.1.47",
  </code></pre>
  
  <p><em>NOTE: It runs successfully with just ng build.</em></p>