### 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
item_remove_button->connect("pressed", callable_mp(this, &ThemeTypeEditor::_item_remove_cbk).bind(p_data_type, p_item_name));
		Button *item_rename_confirm_button = memnew(Button);
		item_rename_confirm_button->set_icon(get_theme_icon(SNAME("ImportCheck"), SNAME("EditorIcons")));
		item_rename_confirm_button->set_tooltip_text(TTR("Confirm Item Rename"));
		item_rename_confirm_button->set_flat(true);
		item_name_container->add_child(item_rename_confirm_button);
		item_rename_confirm_button->connect("pressed", callable_mp(this, &ThemeTypeEditor::_item_rename_confirmed).bind(p_data_type, p_item_name, item_name_container));
		item_rename_confirm_button->hide();
		Button *item_rename_cancel_button = memnew(Button);
		item_rename_cancel_button->set_icon(get_theme_icon(SNAME("ImportFail"), SNAME("EditorIcons")));
		item_rename_cancel_button->set_tooltip_text(TTR("Cancel Item Rename"));
		item_rename_cancel_button->set_flat(true);
		item_name_container->add_child(item_rename_cancel_button);
		item_rename_cancel_button->connect("pressed", callable_mp(this, &ThemeTypeEditor::_item_rename_canceled).bind(p_data_type, p_item_name, item_name_container));
		item_rename_cancel_button->hide();
	} else {
		item_name->add_theme_color_override("font_color", get_theme_color(SNAME("disabled_font_color"), SNAME("Editor")));
		Button *item_override_button = memnew(Button);
		item_override_button->set_icon(get_theme_icon(SNAME("Add"), SNAME("EditorIcons")));
		item_override_button->set_tooltip_text(TTR("Override Item"));
		item_override_button->set_flat(true);
		item_name_container->add_child(item_override_button);
		item_override_button->connect("pressed", callable_mp(this, &ThemeTypeEditor::_item_override_cbk).bind(p_data_type, p_item_name));
	}
	return item_control;
}
void ThemeTypeEditor::_add_focusable(Control *p_control) {
	focusables.append(p_control);
}
void ThemeTypeEditor::_update_type_items() {