### 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
Ref<InputEventMouseButton> b = p_event;
	Ref<InputEventMouseMotion> m = p_event;
	Ref<InputEventKey> k = p_event;
	if (drag_type == DRAG_NONE) {
		if (b.is_valid() && b->is_pressed() &&
				((b->get_button_index() == MouseButton::RIGHT && b->is_alt_pressed() && tool == TOOL_SELECT) ||
						(b->get_button_index() == MouseButton::LEFT && tool == TOOL_LIST_SELECT))) {
			
			Point2 click = transform.affine_inverse().xform(b->get_position());
			_get_canvas_items_at_pos(click, selection_results, b->is_alt_pressed() && tool == TOOL_SELECT);