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.
const bar = new ProgressBar("#loadingBar");
    return shadow(this, "loadingBar", bar);
  },
  get supportedMouseWheelZoomModifierKeys() {
    return this.externalServices.supportedMouseWheelZoomModifierKeys;
  },
  initPassiveLoading() {
    if (
      typeof PDFJSDev === "undefined" ||
      !PDFJSDev.test("MOZCENTRAL || CHROME")
    ) {
      throw new Error("Not implemented: initPassiveLoading");
    }
    this.externalServices.initPassiveLoading({
      onOpenWithTransport: (url, length, transport) => {
        this.open(url, { length, range: transport });
      },
      onOpenWithData: (data, contentDispositionFilename) => {
        if (isPdfFile(contentDispositionFilename)) {
          this._contentDispositionFilename = contentDispositionFilename;
        }
        this.open(data);
      },
      onOpenWithURL: (url, length, originalUrl) => {
        const file = originalUrl !== undefined ? { url, originalUrl } : url;
        const args = length !== undefined ? { length } : null;
        this.open(file, args);
      },