### 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)

if (!is_inside_tree()) {
		return;
	}
	updating_theme = true;
	if (sub_inspector != nullptr) {
		int count_subinspectors = 0;
		Node *n = get_parent();
		while (n) {
			EditorInspector *ei = Object::cast_to<EditorInspector>(n);
			if (ei && ei->is_sub_inspector()) {
				count_subinspectors++;
			}
			n = n->get_parent();
		}
		count_subinspectors = MIN(15, count_subinspectors);
		add_theme_color_override("property_color", get_theme_color(SNAME("sub_inspector_property_color"), SNAME("Editor")));
		add_theme_style_override("bg_selected", get_theme_stylebox("sub_inspector_property_bg" + itos(count_subinspectors), SNAME("Editor")));
		add_theme_style_override("bg", get_theme_stylebox("sub_inspector_property_bg" + itos(count_subinspectors), SNAME("Editor")));
		add_theme_constant_override("v_separation", 0);
	} else {
		add_theme_color_override("property_color", get_theme_color(SNAME("property_color"), SNAME("EditorProperty")));
		add_theme_style_override("bg_selected", get_theme_stylebox(SNAME("bg_selected"), SNAME("EditorProperty")));
		add_theme_style_override("bg", get_theme_stylebox(SNAME("bg"), SNAME("EditorProperty")));
		add_theme_constant_override("v_separation", get_theme_constant(SNAME("v_separation"), SNAME("EditorProperty")));
	}
	updating_theme = false;
	queue_redraw();
}
void EditorPropertyResource::_update_preferred_shader() {