Undefined nodes are currently drawn using a red alert theme color to make it easier to spot them and replace them. On the other hand, nodes that are unsupported, that is, nodes whose poll method fail, are not reported to the user in any way. So this patch also uses the same red alert color for unsupported nodes. The node_type_is_undefined function is moved to the draw file since it seems to be specific to it and not used anywhere else. Pull Request: https://projects.blender.org/blender/blender/pulls/136451