title: Angular throwing NullInjection error only on production
body: <pre><code>ERROR Error: Uncaught (in promise): NullInjectorError: StaticInjectorError(r)[Uw]: 
    StaticInjectorError(Platform: core)[Uw]: 
      NullInjectorError: No provider for Uw!
  NullInjectorError: StaticInjectorError(r)[Uw]: 
    StaticInjectorError(Platform: core)[Uw]: 
      NullInjectorError: No provider for Uw!
  </code></pre>
  
  <p>In <code>app.module.ts</code>:-</p>
  
  <pre><code>providers: [
      PageService,
      SortService,
      FilterService,
      GroupService,
      EditService,
      ToolbarService,
      SelectionService,
      PdfExportService,
      ExcelExportService,
      ConfigService,
      FreezeService,
      ParticipantsService,
    ],
  </code></pre>
  
  <p>All services are present in app.module.ts.
  Importing httpClientModule,HttpModule. </p>
  
  <p>Working fine on localhost, only in production it throws error.</p>