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.
const store = PDFViewerApplication.store;
  if (store && PDFViewerApplication.isInitialViewSet) {
    
    store.set("scrollMode", evt.mode).catch(function () {});
  }
}
function webViewerSpreadModeChanged(evt) {
  const store = PDFViewerApplication.store;
  if (store && PDFViewerApplication.isInitialViewSet) {
    
    store.set("spreadMode", evt.mode).catch(function () {});
  }
}
function webViewerResize() {
  const { pdfDocument, pdfViewer } = PDFViewerApplication;
  if (!pdfDocument) {
    return;
  }
  const currentScaleValue = pdfViewer.currentScaleValue;
  if (
    currentScaleValue === "auto" ||
    currentScaleValue === "page-fit" ||
    currentScaleValue === "page-width"
  ) {
    
    pdfViewer.currentScaleValue = currentScaleValue;
  }
  pdfViewer.update();
}
function webViewerHashchange(evt) {