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.
function downloadByUrl() {
      downloadManager.downloadUrl(url, filename);
    }
    const downloadManager = this.downloadManager,
      url = this.baseUrl,
      filename = this._docFilename;
    
    
    if (!this.pdfDocument || !this.downloadComplete) {
      downloadByUrl();
      return;
    }
    this.pdfDocument
      .getData()
      .then(function (data) {
        const blob = new Blob([data], { type: "application/pdf" });
        downloadManager.download(blob, url, filename, sourceEventType);
      })
      .catch(downloadByUrl); 
  },
  async save({ sourceEventType = "download" } = {}) {