### 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)

}
}
void EditorPropertyResource::update_property() {
	Ref<Resource> res = get_edited_property_value();
	if (use_sub_inspector) {
		if (res.is_valid() != resource_picker->is_toggle_mode()) {
			resource_picker->set_toggle_mode(res.is_valid());
		}
		if (res.is_valid() && get_edited_object()->editor_is_section_unfolded(get_edited_property())) {
			if (!sub_inspector) {
				sub_inspector = memnew(EditorInspector);
				sub_inspector->set_vertical_scroll_mode(ScrollContainer::SCROLL_MODE_DISABLED);
				sub_inspector->set_use_doc_hints(true);
				sub_inspector->set_sub_inspector(true);
				sub_inspector->set_property_name_style(InspectorDock::get_singleton()->get_property_name_style());
				sub_inspector->connect("property_keyed", callable_mp(this, &EditorPropertyResource::_sub_inspector_property_keyed));
				sub_inspector->connect("resource_selected", callable_mp(this, &EditorPropertyResource::_sub_inspector_resource_selected));
				sub_inspector->connect("object_id_selected", callable_mp(this, &EditorPropertyResource::_sub_inspector_object_id_selected));
				sub_inspector->set_keying(is_keying());
				sub_inspector->set_read_only(is_read_only());
				sub_inspector->set_use_folding(is_using_folding());
				sub_inspector_vbox = memnew(VBoxContainer);
				add_child(sub_inspector_vbox);
				set_bottom_editor(sub_inspector_vbox);
				sub_inspector_vbox->add_child(sub_inspector);
				resource_picker->set_toggle_pressed(true);
				Array editor_list;
				for (int i = 0; i < EditorNode::get_editor_data().get_editor_plugin_count(); i++) {
					EditorPlugin *ep = EditorNode::get_editor_data().get_editor_plugin(i);
					if (ep->handles(res.ptr())) {