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.
break;
      case 71: 
        
        PDFViewerApplication.appConfig.toolbar.pageNumber.select();
        handled = true;
        break;
    }
  }
  if (handled) {
    if (ensureViewerFocused && !isViewerInPresentationMode) {
      pdfViewer.focus();
    }
    evt.preventDefault();
    return;
  }
  
  
  const curElement = getActiveOrFocusedElement();
  const curElementTagName = curElement?.tagName.toUpperCase();
  if (
    curElementTagName === "INPUT" ||
    curElementTagName === "TEXTAREA" ||
    curElementTagName === "SELECT" ||
    curElement?.isContentEditable
  ) {
    
    if (evt.keyCode !==  27) {
      return;
    }
  }