### 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
container->add_child(child_container);
		label = memnew(Label);
		label->set_text(TTR("Primary Line Every:"));
		label->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		child_container->add_child(label);
		primary_grid_steps = memnew(SpinBox);
		primary_grid_steps->set_min(0);
		primary_grid_steps->set_step(1);
		primary_grid_steps->set_max(100);
		primary_grid_steps->set_allow_greater(true);
		primary_grid_steps->set_suffix(TTR("steps"));
		primary_grid_steps->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		primary_grid_steps->set_select_all_on_focus(true);
		child_container->add_child(primary_grid_steps);
		container->add_child(memnew(HSeparator));
		
		
		child_container = memnew(GridContainer);
		child_container->set_columns(2);
		container->add_child(child_container);
		label = memnew(Label);
		label->set_text(TTR("Rotation Offset:"));
		child_container->add_child(label);
		label->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		rotation_offset = memnew(SpinBox);
		rotation_offset->set_min(-SPIN_BOX_ROTATION_RANGE);
		rotation_offset->set_max(SPIN_BOX_ROTATION_RANGE);
		rotation_offset->set_suffix("deg");
		rotation_offset->set_h_size_flags(Control::SIZE_EXPAND_FILL);
		rotation_offset->set_select_all_on_focus(true);