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.
});
      
      
      pdfViewer.optionalContentConfigPromise.then(optionalContentConfig => {
        if (pdfDocument !== this.pdfDocument) {
          return; 
        }
        this.pdfLayerViewer.render({ optionalContentConfig, pdfDocument });
      });
      if (
        (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) ||
        "requestIdleCallback" in window
      ) {
        const callback = window.requestIdleCallback(
          () => {
            this._collectTelemetry(pdfDocument);
            this._idleCallbacks.delete(callback);
          },
          { timeout: 1000 }
        );
        this._idleCallbacks.add(callback);
      }
    });
    this._initializePageLabels(pdfDocument);
    this._initializeMetadata(pdfDocument);
  },
  /**
   * @private
   */
  async _scriptingDocProperties(pdfDocument) {