### 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)

}
	}
	return output;
}
int EditorInspectorArray::_drop_position() const {
	for (int i = 0; i < (int)array_elements.size(); i++) {
		const ArrayElement &ae = array_elements[i];
		Size2 size = ae.panel->get_size();
		Vector2 mp = ae.panel->get_local_mouse_position();
		if (Rect2(Vector2(), size).has_point(mp)) {
			if (mp.y < size.y / 2) {
				return i;
			} else {
				return i + 1;
			}
		}
	}
	return -1;
}
void EditorInspectorArray::_resize_dialog_confirmed() {
	if (int(new_size_spin_box->get_value()) == count) {
		return;
	}
	resize_dialog->hide();
	_resize_array(int(new_size_spin_box->get_value()));
}
void EditorInspectorArray::_new_size_spin_box_value_changed(float p_value) {
	resize_dialog->get_ok_button()->set_disabled(int(p_value) == count);
}
void EditorInspectorArray::_new_size_spin_box_text_submitted(String p_text) {