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 { stats } = this.pdfDocument;
    if (stats !== this._docStats) {
      this._docStats = stats;
      this.externalServices.reportTelemetry({
        type: "documentStats",
        stats,
      });
    }
  },
  /**
   * Used together with the integration-tests, to enable awaiting full
   * initialization of the scripting/sandbox.
   */
  get scriptingReady() {
    return this.pdfScriptingManager.ready;
  },
};
let validateFileURL;
if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
  const HOSTED_VIEWER_ORIGINS = [
    "null",
    "http://mozilla.github.io",
    "https://mozilla.github.io",