237babd2e8
Grease pencil modifiers were using a default weight of 1.0 if the influence vertex group is not found. Whether or not that is correct depends on whether a vertex group is set (name not empty). In case the name is set but the group is not found a weight of zero should be used. This can happen in GP3 when no vertex is assigned to a vertex group, since each drawing only has a subset of all the vertex groups. A utility function was added to make this consistent and less error prone. Pull Request: https://projects.blender.org/blender/blender/pulls/117671