### 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
if (p_game_running) {
		override_camera_button->set_disabled(false);
		override_camera_button->set_tooltip_text(TTR("Project Camera Override\nOverrides the running project's camera with the editor viewport camera."));
	} else {
		override_camera_button->set_disabled(true);
		override_camera_button->set_pressed(false);
		override_camera_button->set_tooltip_text(TTR("Project Camera Override\nNo project instance running. Run the project from the editor to use this feature."));
	}
}
void CanvasItemEditor::_popup_callback(int p_op) {
	EditorUndoRedoManager *undo_redo = EditorUndoRedoManager::get_singleton();
	last_option = MenuOption(p_op);
	switch (p_op) {
		case SHOW_ORIGIN: {
			show_origin = !show_origin;
			int idx = view_menu->get_popup()->get_item_index(SHOW_ORIGIN);
			view_menu->get_popup()->set_item_checked(idx, show_origin);
			viewport->queue_redraw();
		} break;
		case SHOW_VIEWPORT: {
			show_viewport = !show_viewport;
			int idx = view_menu->get_popup()->get_item_index(SHOW_VIEWPORT);
			view_menu->get_popup()->set_item_checked(idx, show_viewport);