### 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)

}
EditorPropertyMultilineText::EditorPropertyMultilineText(bool p_expression) {
	HBoxContainer *hb = memnew(HBoxContainer);
	hb->add_theme_constant_override("separation", 0);
	add_child(hb);
	set_bottom_editor(hb);
	text = memnew(TextEdit);
	text->connect("text_changed", callable_mp(this, &EditorPropertyMultilineText::_text_changed));
	text->set_line_wrapping_mode(TextEdit::LineWrappingMode::LINE_WRAPPING_BOUNDARY);
	add_focusable(text);
	hb->add_child(text);
	text->set_h_size_flags(SIZE_EXPAND_FILL);
	open_big_text = memnew(Button);
	open_big_text->set_flat(true);
	open_big_text->connect("pressed", callable_mp(this, &EditorPropertyMultilineText::_open_big_text));
	hb->add_child(open_big_text);
	big_text_dialog = nullptr;
	big_text = nullptr;
	if (p_expression) {
		expression = true;
		Ref<EditorStandardSyntaxHighlighter> highlighter;
		highlighter.instantiate();
		text->set_syntax_highlighter(highlighter);
	}
}
void EditorPropertyTextEnum::_set_read_only(bool p_read_only) {