Since #12241 we have notifications for this when the user navigates away from the viewer, but we do not yet warn when switching documents, which means that if you call e.g. `PDFViewerApplication.open` with a new document (or directly call `BaseViewer.setDocument` when using the viewer components standalone) there won't be any warning about losing form data. This should be addressed.
storedHash,
    { rotation, sidebarView, scrollMode, spreadMode } = {}
  ) {
    const setRotation = angle => {
      if (isValidRotation(angle)) {
        this.pdfViewer.pagesRotation = angle;
      }
    };
    const setViewerModes = (scroll, spread) => {
      if (isValidScrollMode(scroll)) {
        this.pdfViewer.scrollMode = scroll;
      }
      if (isValidSpreadMode(spread)) {
        this.pdfViewer.spreadMode = spread;
      }
    };
    this.isInitialViewSet = true;
    this.pdfSidebar.setInitialView(sidebarView);
    setViewerModes(scrollMode, spreadMode);
    if (this.initialBookmark) {
      setRotation(this.initialRotation);
      delete this.initialRotation;
      this.pdfLinkService.setHash(this.initialBookmark);