message: Fix display of image messages that lack thumbnails
  Fixes
diff: @@ -67,6 +67,7 @@ export class MediaEventHelper implements IDestroyable {
  private prepareThumbnailUrl = async () => {
  if (this.media.isEncrypted) {
  const blob = await this.thumbnailBlob.value;
  + if (blob === null) return null;
  return URL.createObjectURL(blob);
  } else {
  return this.media.thumbnailHttp;
  