### 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 (res.is_null()) {
						continue;
					}
					Ref<PackedScene> scn = res;
					if (scn.is_valid()) {
						Node *instantiated_scene = scn->instantiate(PackedScene::GEN_EDIT_STATE_INSTANCE);
						if (!instantiated_scene) {
							continue;
						}
						memdelete(instantiated_scene);
					}
					can_instantiate = true;
					break;
				}
			}
			if (can_instantiate) {
				if (!preview_node->get_parent()) { // create preview only once
					_create_preview(files);
				}
				Transform2D trans = canvas_item_editor->get_canvas_transform();
				preview_node->set_position((p_point - trans.get_origin()) / trans.get_scale().x);
				label->set_text(vformat(TTR("Adding %s..."), default_texture_node_type));
			}
			return can_instantiate;
		}
	}
	label->hide();
	return false;
}
void CanvasItemEditorViewport::_show_resource_type_selector() {