### Godot version

v4.0.beta.custom_build [eaf306e0b]

### System information

Windows 10

### Issue description

Selecting a `Window` node in the Editor's SceneTree results in the message
```
editor/editor_data.cpp:1058 - Parameter "p_node" is null.
```
and the Inspector shows empty content instead of the Window's properties.

I would expect, that clicking on a node in the SceneTree lets me edit the properties of the node.

Bisecting shows that this behavior got introduced in #71770

### Steps to reproduce

1. Create a Window node
2. Click on the Window node in the Editor's SceneTree

### Minimal reproduction project

N/A
Ref<StyleBox> stylebox;
	if (Object::cast_to<EditorResourcePicker>(p_editor)) {
		stylebox = Object::cast_to<EditorResourcePicker>(p_editor)->get_edited_resource();
	}
	EditorUndoRedoManager *ur = EditorUndoRedoManager::get_singleton();
	ur->create_action(TTR("Pin Stylebox"));
	ur->add_do_method(this, "_pin_leading_stylebox", p_item_name, stylebox);
	if (leading_stylebox.pinned) {
		ur->add_undo_method(this, "_pin_leading_stylebox", leading_stylebox.item_name, leading_stylebox.stylebox);
	} else {
		ur->add_undo_method(this, "_unpin_leading_stylebox");
	}
	ur->commit_action();
}
void ThemeTypeEditor::_pin_leading_stylebox(String p_item_name, Ref<StyleBox> p_stylebox) {
	if (leading_stylebox.stylebox.is_valid()) {
		leading_stylebox.stylebox->disconnect("changed", callable_mp(this, &ThemeTypeEditor::_update_stylebox_from_leading));
	}
	LeadingStylebox leader;
	leader.pinned = true;
	leader.item_name = p_item_name;
	leader.stylebox = p_stylebox;
	leader.ref_stylebox = (p_stylebox.is_valid() ? p_stylebox->duplicate() : Ref<Resource>());
	leading_stylebox = leader;
	if (p_stylebox.is_valid()) {
		p_stylebox->connect("changed", callable_mp(this, &ThemeTypeEditor::_update_stylebox_from_leading));
	}
	_update_type_items();
}
void ThemeTypeEditor::_on_unpin_leader_button_pressed() {