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.
scrollMode = stored.scrollMode | 0;
            }
            if (spreadMode === SpreadMode.UNKNOWN) {
              spreadMode = stored.spreadMode | 0;
            }
          }
          
          if (pageMode && sidebarView === SidebarView.UNKNOWN) {
            sidebarView = apiPageModeToSidebarView(pageMode);
          }
          if (
            pageLayout &&
            scrollMode === ScrollMode.UNKNOWN &&
            spreadMode === SpreadMode.UNKNOWN
          ) {
            const modes = apiPageLayoutToViewerModes(pageLayout);
            
            
            
            spreadMode = modes.spreadMode;
          }
          this.setInitialView(hash, {
            rotation,
            sidebarView,
            scrollMode,
            spreadMode,
          });
          this.eventBus.dispatch("documentinit", { source: this });