### 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)

if (!selected || !p_event->is_pressed()) {
		return;
	}
	const Ref<InputEventKey> k = p_event;
	if (k.is_valid() && k->is_pressed()) {
		if (ED_IS_SHORTCUT("property_editor/copy_value", p_event)) {
			menu_option(MENU_COPY_VALUE);
			accept_event();
		} else if (ED_IS_SHORTCUT("property_editor/paste_value", p_event) && !is_read_only()) {
			menu_option(MENU_PASTE_VALUE);
			accept_event();
		} else if (ED_IS_SHORTCUT("property_editor/copy_property_path", p_event)) {
			menu_option(MENU_COPY_PROPERTY_PATH);
			accept_event();
		}
	}
}
const Color *EditorProperty::_get_property_colors() {
	static Color c[4];
	c[0] = get_theme_color(SNAME("property_color_x"), SNAME("Editor"));
	c[1] = get_theme_color(SNAME("property_color_y"), SNAME("Editor"));
	c[2] = get_theme_color(SNAME("property_color_z"), SNAME("Editor"));
	c[3] = get_theme_color(SNAME("property_color_w"), SNAME("Editor"));
	return c;
}
void EditorProperty::set_label_reference(Control *p_control) {
	label_reference = p_control;
}
void EditorProperty::set_bottom_editor(Control *p_control) {