There are two issues here. First, the instanced panel freeing uses
the panel type after it's been freed a few lines up in this function.
Second, while panel types are registered for a single space type,
there are cases where they're used in multiple space/region types
anyway. Because of that, removing the dangling pointer of the freed
type from just the registered region & space type combination isn't
enough, we need to process all regions.
Pull Request: https://projects.blender.org/blender/blender/pulls/129676
37e35147d8