### 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)

ERR_FAIL_COND(p_paths.size() == 0 || p_values.size() == 0);
	ERR_FAIL_COND(p_paths.size() != p_values.size());
	String names;
	for (int i = 0; i < p_paths.size(); i++) {
		if (i > 0) {
			names += ",";
		}
		names += p_paths[i];
	}
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	undo_redo->create_action(TTR("Set Multiple:") + " " + names, UndoRedo::MERGE_ENDS);
	for (int i = 0; i < p_paths.size(); i++) {
		_edit_set(p_paths[i], p_values[i], false, "");
		if (restart_request_props.has(p_paths[i])) {
			emit_signal(SNAME("restart_requested"));
		}
	}
	if (p_changing) {
		changing++;
	}
	undo_redo->commit_action();
	if (p_changing) {
		changing--;
	}
}
void EditorInspector::_property_keyed(const String &p_path, bool p_advance) {