### Godot version

4.0-rc6

### System information

Fedora 37, Mesa Intel ADL GT2

### Issue description

Code that works as expected at runtime fails with Nil references to (assigned) exported vars in the editor:

![tool_global_position_error](https://user-images.githubusercontent.com/364501/222031460-ffb1ecbd-5175-4a42-8470-25285ba5f821.png)


### Steps to reproduce

Try to access the `global_position` of a `Node3D` that's assigned to an exported var.

See that it works at runtime.

See that it errors in the editor with:

> Invalid get index 'global_position' (on base: 'Nil').

### Minimal reproduction project

[tool_test.zip](https://github.com/godotengine/godot/files/10856640/tool_test.zip)

custom_value_edit->set_text(get_edited_property_value());
	edit_custom_layout->hide();
	default_layout->show();
}
void EditorPropertyTextEnum::update_property() {
	String current_value = get_edited_property_value();
	int default_option = options.find(current_value);
	
	if (loose_mode) {
		custom_value_edit->set_text(current_value);
		option_button->clear();
		
		if (default_option < 0 && !current_value.is_empty()) {
			option_button->add_item(current_value, options.size() + 1001);
			option_button->select(0);
			option_button->add_separator();
		}
		
		option_button->add_item("", options.size() + 1000);
		for (int i = 0; i < options.size(); i++) {
			option_button->add_item(options[i], i);
			if (options[i] == current_value) {
				option_button->select(option_button->get_item_count() - 1);
			}
		}
	} else {
		option_button->select(default_option);
	}
}
void EditorPropertyTextEnum::setup(const Vector<String> &p_options, bool p_string_name, bool p_loose_mode) {