The poll function for `NODE_PT_node_tree_interface_panel_toggle` looks at the first child item and checks if it has the `is_panel_toggle` property set to `True`. This fails if the first child is a panel, which doesn't have that property. The fix is to simply fall back to returning False if the first child item does not have the aforementioned property. Pull Request: https://projects.blender.org/blender/blender/pulls/137171