When converting GPv3 object with zero drawings to curves, Blender crashes
due to accessing invalid drawing/offset value.
With `curve to mesh` node, the evaluated `gemoetry_set` had
a dummy GPv3 object data with zero drawings, see
`BKE_grease_pencil_data_update`. Hence, the crash in
`object_convert_exec` while accessing the offset array.
Pull Request: https://projects.blender.org/blender/blender/pulls/123067
950f5eef91