### 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
VBoxContainer *items_tab = memnew(VBoxContainer);
	items_tab->set_custom_minimum_size(Size2(0, 160) * EDSCALE);
	data_type_tabs->add_child(items_tab);
	data_type_tabs->set_tab_title(data_type_tabs->get_tab_count() - 1, "");
	ScrollContainer *items_sc = memnew(ScrollContainer);
	items_sc->set_v_size_flags(SIZE_EXPAND_FILL);
	items_sc->set_horizontal_scroll_mode(ScrollContainer::SCROLL_MODE_DISABLED);
	items_tab->add_child(items_sc);
	VBoxContainer *items_list = memnew(VBoxContainer);
	items_list->set_h_size_flags(SIZE_EXPAND_FILL);
	items_sc->add_child(items_list);
	HBoxContainer *item_add_hb = memnew(HBoxContainer);
	items_tab->add_child(item_add_hb);
	LineEdit *item_add_edit = memnew(LineEdit);
	item_add_edit->set_h_size_flags(SIZE_EXPAND_FILL);
	item_add_hb->add_child(item_add_edit);
	item_add_edit->connect("text_submitted", callable_mp(this, &ThemeTypeEditor::_item_add_lineedit_cbk).bind(p_data_type, item_add_edit));
	Button *item_add_button = memnew(Button);
	item_add_button->set_text(TTR("Add"));
	item_add_hb->add_child(item_add_button);
	item_add_button->connect("pressed", callable_mp(this, &ThemeTypeEditor::_item_add_cbk).bind(p_data_type, item_add_edit));
	return items_list;
}
void ThemeTypeEditor::_update_type_list() {