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.
fileInput: evt.dataTransfer,
      });
    });
  } else {
    appConfig.toolbar.openFile.hidden = true;
    appConfig.secondaryToolbar.openFileButton.hidden = true;
  }
  if (!PDFViewerApplication.supportsDocumentFonts) {
    AppOptions.set("disableFontFace", true);
    PDFViewerApplication.l10n.get("web_fonts_disabled").then(msg => {
      console.warn(msg);
    });
  }
  if (!PDFViewerApplication.supportsPrinting) {
    appConfig.toolbar.print.classList.add("hidden");
    appConfig.secondaryToolbar.printButton.classList.add("hidden");
  }
  if (!PDFViewerApplication.supportsFullscreen) {
    appConfig.toolbar.presentationModeButton.classList.add("hidden");
    appConfig.secondaryToolbar.presentationModeButton.classList.add("hidden");
  }
  if (PDFViewerApplication.supportsIntegratedFind) {
    appConfig.toolbar.viewFind.classList.add("hidden");
  }
  appConfig.mainContainer.addEventListener(
    "transitionend",
    function (evt) {
      if (evt.target ===  this) {
        PDFViewerApplication.eventBus.dispatch("resize", { source: this });
      }