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.
parameters.url = file.url;
    }
    
    const apiParameters = AppOptions.getAll(OptionKind.API);
    for (const key in apiParameters) {
      let value = apiParameters[key];
      if (key === "docBaseUrl" && !value) {
        if (typeof PDFJSDev === "undefined" || !PDFJSDev.test("PRODUCTION")) {
          value = document.URL.split("#")[0];
        } else if (PDFJSDev.test("MOZCENTRAL || CHROME")) {
          value = this.baseUrl;
        }
      }
      parameters[key] = value;
    }
    
    if (args) {
      for (const key in args) {
        parameters[key] = args[key];
      }
    }
    const loadingTask = getDocument(parameters);
    this.pdfLoadingTask = loadingTask;
    loadingTask.onPassword = (updateCallback, reason) => {
      this.pdfLinkService.externalLinkEnabled = false;
      this.passwordPrompt.setUpdateCallback(updateCallback, reason);
      this.passwordPrompt.open();
    };
    loadingTask.onProgress = ({ loaded, total }) => {
      this.progress(loaded / total);