Follow-up fix for #113330. The `valid_socket_type` classmethod in node trees is only available on custom node trees (but documentation does not say that). It cannot be used to determine if the default float socket type is valid for built-in node tree types. We have to assume this socket type is always valid for built-in node trees, or the operator will try to call a non-existent method. Pull Request: https://projects.blender.org/blender/blender/pulls/113540