Crash when exporting selected frames due to two different reason. frame returned by frame_at() can be null, so add a null check before calling `is_selected()` member function. After depsgraph update, ob_eval.data changes. So cast it to gease_pencil every frame to avoid the crash (otherwise grease_pencil will point to invalid memory). Pull Request: https://projects.blender.org/blender/blender/pulls/126643