### Godot version

v4.0.beta17.mono.official [c40020513]

### System information

Window 11, Forward+, GTX 1060

### Issue description

Adding two theme variations in a row result to a  crash.

https://user-images.githubusercontent.com/93253123/217037249-1ce1d56d-beb6-4435-83ad-9f8a07fe0e96.mp4



### Steps to reproduce

1. Create a project.
2. Create a theme.
3. Double click to go in the theme editor.
4. Click on manage items buttons.
5. In the add type field type a name to add a type.
6. type another name to add a second type.
7. Crash.

### Minimal reproduction project

[ThemeVariationCrash.zip](https://github.com/godotengine/godot/files/10665863/ThemeVariationCrash.zip)

emit_signal(SNAME("object_id_selected"), p_id);
}
void EditorInspector::_resource_selected(const String &p_path, Ref<Resource> p_resource) {
	emit_signal(SNAME("resource_selected"), p_resource, p_path);
}
void EditorInspector::_node_removed(Node *p_node) {
	if (p_node == object) {
		edit(nullptr);
	}
}
void EditorInspector::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_READY: {
			EditorFeatureProfileManager::get_singleton()->connect("current_feature_profile_changed", callable_mp(this, &EditorInspector::_feature_profile_changed));
			set_process(is_visible_in_tree());
			_update_inspector_bg();
		} break;
		case NOTIFICATION_ENTER_TREE: {
			if (!sub_inspector) {
				get_tree()->connect("node_removed", callable_mp(this, &EditorInspector::_node_removed));
			}
		} break;
		case NOTIFICATION_PREDELETE: {
			edit(nullptr); 
		} break;