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.
onError: err => {
        this.l10n.get("loading_error").then(msg => {
          this._documentError(msg, err);
        });
      },
      onProgress: (loaded, total) => {
        this.progress(loaded / total);
      },
    });
  },
  setTitleUsingUrl(url = "", downloadUrl = null) {
    this.url = url;
    this.baseUrl = url.split("#")[0];
    if (downloadUrl) {
      this._downloadUrl =
        downloadUrl === url ? this.baseUrl : downloadUrl.split("#")[0];
    }
    let title = getPdfFilenameFromUrl(url, "");
    if (!title) {
      try {
        title = decodeURIComponent(getFilenameFromUrl(url)) || url;
      } catch (ex) {
        
        
        title = url;
      }
    }
    this.setTitle(title);
  },
  setTitle(title) {