### 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
int e_idx = 0;
		for (const StringName &E : theme_types) {
			Ref<Texture2D> item_icon;
			if (E == "") {
				item_icon = get_theme_icon(SNAME("NodeDisabled"), SNAME("EditorIcons"));
			} else {
				item_icon = EditorNode::get_singleton()->get_class_icon(E, "NodeDisabled");
			}
			theme_type_list->add_icon_item(item_icon, E);
			if (E == edited_type) {
				theme_type_list->select(e_idx);
				item_reselected = true;
			}
			e_idx++;
		}
		if (!item_reselected) {
			theme_type_list->select(0);
			_list_type_selected(0);
		} else {
			_update_type_items();
		}
	} else {
		theme_type_list->set_disabled(true);
		theme_type_list->add_item(TTR("None"));
		edited_type = "";
		_update_type_items();
	}
	updating = false;
}
void ThemeTypeEditor::_update_type_list_debounced() {