df251784cd
When the PBVH is rebuilt, the `active_face_index` and `active_grid_index` fields are initialized to -1. This results in a possible segmentation fault if the `active_face_set_get` method is called without these fields being populated. This commit switches the raw `int` usage for `std::optional` to better communicate the intent of these fields. Pull Request: https://projects.blender.org/blender/blender/pulls/127959