fix: don't show create stream if file size is null

mobile/apps/photos/lib/ui/viewer/file/file_app_bar.dart

@@ -497,6 +497,7 @@ class FileAppBarState extends State<FileAppBar> {
     final userId = Configuration.instance.getUserID();
     return widget.file.fileType == FileType.video &&
         widget.file.isUploaded &&
+        widget.file.fileSize != null &&
         (widget.file.pubMagicMetadata?.sv ?? 0) != 1 &&
         widget.file.ownerID == userId;
   }