### 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;
	
	if (drag_type == DRAG_NONE) {
		if (b.is_valid() && b->get_button_index() == MouseButton::LEFT && b->is_pressed() && tool == TOOL_SELECT) {
			List<CanvasItem *> selection = _get_edited_canvas_items();
			if (selection.size() == 1) {
				CanvasItem *ci = selection[0];
				if (ci->_edit_use_rect() && _is_node_movable(ci)) {
					Rect2 rect = ci->_edit_get_rect();
					Transform2D xform = transform * ci->get_global_transform_with_canvas();
					const Vector2 endpoints[4] = {
						xform.xform(rect.position),
						xform.xform(rect.position + Vector2(rect.size.x, 0)),
						xform.xform(rect.position + rect.size),
						xform.xform(rect.position + Vector2(0, rect.size.y))
					};
					const DragType dragger[] = {
						DRAG_TOP_LEFT,
						DRAG_TOP,
						DRAG_TOP_RIGHT,
						DRAG_RIGHT,
						DRAG_BOTTOM_RIGHT,
						DRAG_BOTTOM,
						DRAG_BOTTOM_LEFT,
						DRAG_LEFT
					};
					DragType resize_drag = DRAG_NONE;