STR:
  - Go to https://mozilla.github.io/pdf.js/web/viewer.html
  - Click on "Open File" and open a pdf

The `Download` button and the `Current view` one just disappear.
I can reproduce this bug with Firefox nightly, Chrome stable and Epiphany on debian.
this.disableAutoFetchLoadingBarTimeout = null;
        }
        this.loadingBar.show();
        this.disableAutoFetchLoadingBarTimeout = setTimeout(() => {
          this.loadingBar.hide();
          this.disableAutoFetchLoadingBarTimeout = null;
        }, DISABLE_AUTO_FETCH_LOADING_BAR_TIMEOUT);
      }
    }
  },
  load(pdfDocument) {
    this.pdfDocument = pdfDocument;
    pdfDocument.getDownloadInfo().then(({ length }) => {
      this._contentLength = length; 
      this.downloadComplete = true;
      this.loadingBar.hide();
      firstPagePromise.then(() => {
        this.eventBus.dispatch("documentloaded", { source: this });
      });
    });
    
    
    const pageLayoutPromise = pdfDocument.getPageLayout().catch(function () {
      
    });
    const pageModePromise = pdfDocument.getPageMode().catch(function () {
      
    });
    const openActionPromise = pdfDocument.getOpenAction().catch(function () {