### 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)

GDCLASS(EditorPropertyRID, EditorProperty);
	Label *label = nullptr;
public:
	virtual void update_property() override;
	EditorPropertyRID();
};
class EditorPropertyResource : public EditorProperty {
	GDCLASS(EditorPropertyResource, EditorProperty);
	EditorResourcePicker *resource_picker = nullptr;
	SceneTreeDialog *scene_tree = nullptr;
	bool use_sub_inspector = false;
	EditorInspector *sub_inspector = nullptr;
	VBoxContainer *sub_inspector_vbox = nullptr;
	bool updating_theme = false;
	bool opened_editor = false;
	void _resource_selected(const Ref<Resource> &p_resource, bool p_inspect);