### 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 (selection_results.size() <= p_result) {
		return;
	}
	CanvasItem *item = selection_results[p_result].item;
	if (item) {
		_select_click_on_item(item, Point2(), selection_menu_additive_selection);
	}
}
void CanvasItemEditor::_selection_menu_hide() {
	selection_results.clear();
	selection_menu->clear();
	selection_menu->reset_size();
}
void CanvasItemEditor::_add_node_pressed(int p_result) {
	List<Node *> nodes_to_move;
	switch (p_result) {
		case ADD_NODE: {
			SceneTreeDock::get_singleton()->open_add_child_dialog();
		} break;
		case ADD_INSTANCE: {
			SceneTreeDock::get_singleton()->open_instance_child_dialog();
		} break;
		case ADD_PASTE: {
			nodes_to_move = SceneTreeDock::get_singleton()->paste_nodes();
			[[fallthrough]];
		}
		case ADD_MOVE: {
			nodes_to_move = EditorNode::get_singleton()->get_editor_selection()->get_selected_node_list();