### 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)

AABB val = get_edited_property_value();
	setting = true;
	spin[0]->set_value(val.position.x);
	spin[1]->set_value(val.position.y);
	spin[2]->set_value(val.position.z);
	spin[3]->set_value(val.size.x);
	spin[4]->set_value(val.size.y);
	spin[5]->set_value(val.size.z);
	setting = false;
}
void EditorPropertyAABB::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_ENTER_TREE:
		case NOTIFICATION_THEME_CHANGED: {
			const Color *colors = _get_property_colors();
			for (int i = 0; i < 6; i++) {
				spin[i]->add_theme_color_override("label_color", colors[i % 3]);
			}
		} break;
	}
}
void EditorPropertyAABB::_bind_methods() {