### 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)

EASING_ZERO,
		EASING_LINEAR,
		EASING_IN,
		EASING_OUT,
		EASING_IN_OUT,
		EASING_OUT_IN,
		EASING_MAX
	};
	void _drag_easing(const Ref<InputEvent> &p_ev);
	void _draw_easing();
	void _set_preset(int);
	void _setup_spin();
	void _spin_value_changed(double p_value);
	void _spin_focus_exited();
	void _notification(int p_what);
protected:
	virtual void _set_read_only(bool p_read_only) override;
	static void _bind_methods();
public:
	virtual void update_property() override;
	void setup(bool p_positive_only, bool p_flip);
	EditorPropertyEasing();
};
class EditorPropertyRect2 : public EditorProperty {