worker terminates in ng2-pdf-viewer if loading was aborted

in my angular app I have a master detail view. The master is a list of items. By selecting an item I show in the detail pdfs, which belong to the item. For viewing the pdfs I use ng2-pdf-viewer. If I select an other item before all pdfs of the current item are loaded completely, I get the following errors:

Uncaught (in promise) Error: Worker was terminated
    at ensureNotTerminated (pdf.worker.js:sourcemap:274)
    at onFailure (pdf.worker.js:sourcemap:476)

and:

pdf_viewer.js:5606 Unable to initialize viewer Error: Transport destroyed
    at pdf.js:3448
    at ZoneDelegate.invoke (zone-evergreen.js:364)
    at Object.onInvoke (core.js:27149)
    at ZoneDelegate.invoke (zone-evergreen.js:363)
    at Zone.run (zone-evergreen.js:123)
    at zone-evergreen.js:857
    at ZoneDelegate.invokeTask (zone-evergreen.js:399)
    at Object.onInvokeTask (core.js:27137)
    at ZoneDelegate.invokeTask (zone-evergreen.js:398)
    at Zone.runTask (zone-evergreen.js:167)

ERROR Error: Uncaught (in promise): Error: Transport destroyed
Error: Transport destroyed
    at pdf.js:3448
    at ZoneDelegate.invoke (zone-evergreen.js:364)
    at Object.onInvoke (core.js:27149)
    at ZoneDelegate.invoke (zone-evergreen.js:363)
    at Zone.run (zone-evergreen.js:123)
    at zone-evergreen.js:857
    at ZoneDelegate.invokeTask (zone-evergreen.js:399)
    at Object.onInvokeTask (core.js:27137)
    at ZoneDelegate.invokeTask (zone-evergreen.js:398)
    at Zone.runTask (zone-evergreen.js:167)
    at resolvePromise (zone-evergreen.js:798)
    at resolvePromise (zone-evergreen.js:750)
    at zone-evergreen.js:860
    at ZoneDelegate.invokeTask (zone-evergreen.js:399)
    at Object.onInvokeTask (core.js:27137)
    at ZoneDelegate.invokeTask (zone-evergreen.js:398)
    at Zone.runTask (zone-evergreen.js:167)
    at drainMicroTaskQueue (zone-evergreen.js:569)
    at ZoneTask.invokeTask [as invoke] (zone-evergreen.js:484)
    at invokeTask (zone-evergreen.js:1621)

By clicking an other item the old detail component will be destroyed and a new one will be created. For the detail view I have implemented an own previewer component:

<mat-card *ngFor="let document of documentListObs | async" >
      <mat-card-content (click)="showDocument(document)" class="fill-container">
        <pdf-viewer *ngIf="isPdfSource(document)"
          [src]="!abort ? document.fileData : null"
          [original-size]="false"
          [show-all]="false"
          [page]="1"
          [autoresize]="false"
          (error)="onError($event)"
        >
        </pdf-viewer>
      </mat-card-content>
</mat-card>

documentListObs is declared in the typescript code as follows:

  @Input() public documentListObs: Observable<BmdDocument[]>;

I tried to reset the src property of the pdf-viewer to null in the ngOnDestroy of the component ... without any success:

  ngOnDestroy() {
    this.abort = true;
  }

Thanks for helps!