Blender Git Loki

Fix T89899: Crashes when accessing vertex groups from objects

We need to be more strict about trying to retrieve a list of vertex group
names from objects now, as only three object types support them.
This commit adds a check for vertex group support in a few places, the
data transfer operator/modifier, copying vertex groups to selected
objects, and the vertex group remove and clear functions.

Differential Revision: https://developer.blender.org/D11947