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.
return true;
      } catch (ex) {
        console.error(`openOrDownloadData: ${ex}`);
        
        
        URL.revokeObjectURL(blobUrl);
        this._openBlobUrls.delete(element);
      }
    }
    this.downloadData(data, filename, contentType);
    return false;
  }
  /**
   * @param sourceEventType {string} Used to signal what triggered the download.
   *   The version of PDF.js integrated with Firefox uses this to to determine
   *   which dialog to show. "save" triggers "save as" and "download" triggers
   *   the "open with" dialog.
   */
  download(blob, url, filename, sourceEventType = "download") {
    if (compatibilityParams.disableCreateObjectURL) {
      
      this.downloadUrl(url, filename);
      return;
    }
    const blobUrl = URL.createObjectURL(blob);
    download(blobUrl, filename);
  }
}
export { DownloadManager };