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.findController = findController;
    const pdfScriptingManager = new PDFScriptingManager({
      eventBus,
      sandboxBundleSrc:
        typeof PDFJSDev === "undefined" ||
        PDFJSDev.test("!PRODUCTION || GENERIC || CHROME")
          ? AppOptions.get("sandboxBundleSrc")
          : null,
      scriptingFactory: externalServices,
      docPropertiesLookup: this._scriptingDocProperties.bind(this),
    });
    this.pdfScriptingManager = pdfScriptingManager;
    const container = appConfig.mainContainer;
    const viewer = appConfig.viewerContainer;
    this.pdfViewer = new PDFViewer({
      container,
      viewer,
      eventBus,
      renderingQueue: pdfRenderingQueue,
      linkService: pdfLinkService,
      downloadManager,
      findController,
      scriptingManager:
        AppOptions.get("enableScripting") && pdfScriptingManager,
      renderer: AppOptions.get("renderer"),
      l10n: this.l10n,
      textLayerMode: AppOptions.get("textLayerMode"),
      annotationMode: AppOptions.get("annotationMode"),
      imageResourcesPath: AppOptions.get("imageResourcesPath"),