51904839ac
The main reason that didn't work before because undefined custom node groups have the undefined `bNodeType` (and thus are ignored in various places) but are actually still groups that can be evaluated. The fix is just to handle custom node groups a bit more explicitly. In the future, we may want to have a separate "undefined custom group" `bNodetype`, but that might a be a bit bigger project. Pull Request: https://projects.blender.org/blender/blender/pulls/135974