### 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("page_changed", 0);
}
void EditorPaginator::_prev_page_button_pressed() {
	emit_signal("page_changed", MAX(0, page - 1));
}
void EditorPaginator::_page_line_edit_text_submitted(String p_text) {
	if (p_text.is_valid_int()) {
		int new_page = p_text.to_int() - 1;
		new_page = MIN(MAX(0, new_page), max_page);
		page_line_edit->set_text(Variant(new_page));
		emit_signal("page_changed", new_page);
	} else {
		page_line_edit->set_text(Variant(page));
	}
}
void EditorPaginator::_next_page_button_pressed() {
	emit_signal("page_changed", MIN(max_page, page + 1));
}
void EditorPaginator::_last_page_button_pressed() {