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 a = document.createElement("a");
  if (!a.click) {
    throw new Error('DownloadManager: "a.click()" is not supported.');
  }
  a.href = blobUrl;
  a.target = "_parent";
  
  
  if ("download" in a) {
    a.download = filename;
  }
  
  
  (document.body || document.documentElement).appendChild(a);
  a.click();
  a.remove();
}
class DownloadManager {