When using viewer.js code in an iframe (`web/viewer.html?file=my.pdf"`) and getting a load error like `Error: file origin does not match viewer's` how do I catch this error?  The console reports `app.js:2140 Uncaught (in promise) Error: file origin does not match viewer's`.  I have setup the load listener and am using the `PDFViewerApplication.initializedPromise`.  I was hoping the `PDFViewerApplication.initializedPromise` would reject, but it does not.  I could not find an eventbus event to listen to specifically for load errors either.

I would like to programmatically detect such load errors and dynamically remove the iframe hosting the pdf viewer and instead replace it with my own error messaging.  I can't figure out how to do that.

Configuration:
- Any, but testing on Chrome 97.0.4692.71 64-bit
- Ubuntu 20.04
- PDF.js version:  v2.12.313
- Is a browser extension: No

Steps to reproduce the problem:
1.  Purposely try to load a PDF in a way that would cause the `app.js:2140 Uncaught (in promise) Error: file origin does not match viewer's` error.
if (!PDFViewerApplication.secondaryToolbar.isOpen) {
    return;
  }
  const appConfig = PDFViewerApplication.appConfig;
  if (
    PDFViewerApplication.pdfViewer.containsElement(evt.target) ||
    (appConfig.toolbar.container.contains(evt.target) &&
      evt.target !== appConfig.secondaryToolbar.toggleButton)
  ) {
    PDFViewerApplication.secondaryToolbar.close();
  }
}
function webViewerKeyDown(evt) {
  if (PDFViewerApplication.overlayManager.active) {
    return;
  }
  const { eventBus, pdfViewer } = PDFViewerApplication;
  const isViewerInPresentationMode = pdfViewer.isInPresentationMode;
  let handled = false,
    ensureViewerFocused = false;
  const cmd =
    (evt.ctrlKey ? 1 : 0) |
    (evt.altKey ? 2 : 0) |
    (evt.shiftKey ? 4 : 0) |
    (evt.metaKey ? 8 : 0);
  
  
  if (cmd === 1 || cmd === 8 || cmd === 5 || cmd === 12) {
    
    switch (evt.keyCode) {