Cannot read properties of undefined (reading 'length')' Error on adding annotation on pdf

this.adobeDCView.registerCallback(
      window.AdobeDC.View.Enum.CallbackType.SAVE_API,
      async function (metaData, content, options) {
        console.log("inside register callback")
        try {
          await previewFilePromise.then(adobeViewer => {
            adobeViewer.getAnnotationManager().then(annotationManager => {
              annotationManager.getAnnotations()
                .then(result => {
                  setNewAnnotations(result)
                  console.log('annotation:', result)
                }
                )
                .catch(error => console.log(error));
            });
          });
        } catch (e) {
          console.log(e)
        }
        return new Promise((resolve, reject) => {
          resolve({
            code: window.AdobeDC.View.Enum.ApiResponseCode.SUCCESS,
            data: {
              metaData: { fileName: url.slice(42) }
            }
          });
        });
      },
      {
        autoSaveFrequency: 0,
        enableFocusPolling: false,
        showSaveButton: true
      }
    );

Documentation we followed : https://developer.adobe.com/document-services/docs/overview/pdf-embed-api/howtos_ui/#save-callback