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 (cmd === 0) {
    let turnPage = 0,
      turnOnlyIfPageFit = false;
    switch (evt.keyCode) {
      case 38: 
      case 33: 
        
        if (pdfViewer.isVerticalScrollbarEnabled) {
          turnOnlyIfPageFit = true;
        }
        turnPage = -1;
        break;
      case 8: 
        if (!isViewerInPresentationMode) {
          turnOnlyIfPageFit = true;
        }
        turnPage = -1;
        break;
      case 37: 
        
        if (pdfViewer.isHorizontalScrollbarEnabled) {
          turnOnlyIfPageFit = true;
        }
      
      case 75: 
      case 80: 
        turnPage = -1;
        break;
      case 27: