This was a double free error which happened because `BM_mesh_bm_from_me`
was taking ownership of arrays that were still owned by the Mesh. Note that
this only happens when the mesh is empty but some custom data layers still
have a non-null data pointer. While usually the data pointer should be null in
this case for performance reasons, other functions should still be able to
handle this situation.
Differential Revision: https://developer.blender.org/D14181
17e0634902