### 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 read_only;
}
Variant EditorPropertyRevert::get_property_revert_value(Object *p_object, const StringName &p_property, bool *r_is_valid) {
	if (p_object->property_can_revert(p_property)) {
		if (r_is_valid) {
			*r_is_valid = true;
		}
		return p_object->property_get_revert(p_property);
	}
	return PropertyUtils::get_property_default_value(p_object, p_property, r_is_valid);
}
bool EditorPropertyRevert::can_property_revert(Object *p_object, const StringName &p_property, const Variant *p_custom_current_value) {
	bool is_valid_revert = false;
	Variant revert_value = EditorPropertyRevert::get_property_revert_value(p_object, p_property, &is_valid_revert);
	if (!is_valid_revert) {
		return false;
	}
	Variant current_value = p_custom_current_value ? *p_custom_current_value : p_object->get(p_property);
	return PropertyUtils::is_property_value_different(current_value, revert_value);
}
StringName EditorProperty::_get_revert_property() const {
	return property;
}
void EditorProperty::update_editor_property_status() {