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.
evt.preventDefault();
  evt.returnValue = "";
  return false;
}
const PDFPrintServiceFactory = {
  instance: {
    supportsPrinting: false,
    createPrintService() {
      throw new Error("Not implemented: createPrintService");
    },
  },
};
export {
  DefaultExternalServices,
  PDFPrintServiceFactory,
  PDFViewerApplication,
};