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.
});
      pdfDocument.getAttachments().then(attachments => {
        if (pdfDocument !== this.pdfDocument) {
          return; 
        }
        this.pdfAttachmentViewer.render({ attachments });
      });
      
      
      pdfViewer.optionalContentConfigPromise.then(optionalContentConfig => {
        if (pdfDocument !== this.pdfDocument) {
          return; 
        }
        this.pdfLayerViewer.render({ optionalContentConfig, pdfDocument });
      });
      if (
        (typeof PDFJSDev !== "undefined" && PDFJSDev.test("MOZCENTRAL")) ||
        "requestIdleCallback" in window
      ) {
        const callback = window.requestIdleCallback(
          () => {
            this._collectTelemetry(pdfDocument);
            this._idleCallbacks.delete(callback);
          },
          { timeout: 1000 }
        );
        this._idleCallbacks.add(callback);
      }
    });
    this._initializePageLabels(pdfDocument);