### 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)

Ref<EditorFeatureProfile> profile = EditorFeatureProfileManager::get_singleton()->get_current_profile();
	if (profile.is_null()) {
		return false;
	}
	StringName class_name = object->get_class();
	while (class_name != StringName()) {
		if (profile->is_class_property_disabled(class_name, p_property)) {
			return true;
		}
		if (profile->is_class_disabled(class_name)) {
			
			return true;
		}
		class_name = ClassDB::get_parent_class(class_name);
	}
	return false;
}
void EditorInspector::update_tree() {