### 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
const int SPIN_BOX_GRID_RANGE = 16384;
		const int SPIN_BOX_ROTATION_RANGE = 360;
		const real_t SPIN_BOX_SCALE_MIN = 0.01;
		const real_t SPIN_BOX_SCALE_MAX = 100;
		Label *label;
		VBoxContainer *container;
		GridContainer *child_container;
		set_title(TTR("Configure Snap"));
		container = memnew(VBoxContainer);
		add_child(container);
		child_container = memnew(GridContainer);
		child_container->set_columns(3);
		container->add_child(child_container);
		label = memnew(Label);
		label->set_text(TTR("Grid Offset:"));
		child_container->add_child(label);
		label->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		grid_offset_x = memnew(SpinBox);
		grid_offset_x->set_min(-SPIN_BOX_GRID_RANGE);
		grid_offset_x->set_max(SPIN_BOX_GRID_RANGE);
		grid_offset_x->set_allow_lesser(true);
		grid_offset_x->set_allow_greater(true);
		grid_offset_x->set_suffix("px");
		grid_offset_x->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		grid_offset_x->set_select_all_on_focus(true);
		child_container->add_child(grid_offset_x);
		grid_offset_y = memnew(SpinBox);