### 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
add_child(import_buttons);
	import_collapse_types_button = memnew(Button);
	import_collapse_types_button->set_flat(true);
	import_collapse_types_button->set_tooltip_text(TTR("Collapse types."));
	import_buttons->add_child(import_collapse_types_button);
	import_collapse_types_button->connect("pressed", callable_mp(this, &ThemeItemImportTree::_toggle_type_items).bind(true));
	import_expand_types_button = memnew(Button);
	import_expand_types_button->set_flat(true);
	import_expand_types_button->set_tooltip_text(TTR("Expand types."));
	import_buttons->add_child(import_expand_types_button);
	import_expand_types_button->connect("pressed", callable_mp(this, &ThemeItemImportTree::_toggle_type_items).bind(false));
	import_buttons->add_child(memnew(VSeparator));
	import_select_all_button = memnew(Button);
	import_select_all_button->set_flat(true);
	import_select_all_button->set_text(TTR("Select All"));
	import_select_all_button->set_tooltip_text(TTR("Select all Theme items."));
	import_buttons->add_child(import_select_all_button);
	import_select_all_button->connect("pressed", callable_mp(this, &ThemeItemImportTree::_select_all_items_pressed));
	import_select_full_button = memnew(Button);
	import_select_full_button->set_flat(true);
	import_select_full_button->set_text(TTR("Select With Data"));
	import_select_full_button->set_tooltip_text(TTR("Select all Theme items with item data."));
	import_buttons->add_child(import_select_full_button);
	import_select_full_button->connect("pressed", callable_mp(this, &ThemeItemImportTree::_select_full_items_pressed));
	import_deselect_all_button = memnew(Button);
	import_deselect_all_button->set_flat(true);
	import_deselect_all_button->set_text(TTR("Deselect All"));
	import_deselect_all_button->set_tooltip_text(TTR("Deselect all Theme items."));
	import_buttons->add_child(import_deselect_all_button);
	import_deselect_all_button->connect("pressed", callable_mp(this, &ThemeItemImportTree::_deselect_all_items_pressed));