### 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
ur->add_undo_method(*edited_theme, "clear_color", p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_CONSTANT: {
			ur->add_do_method(*edited_theme, "set_constant", p_item_name, edited_type, ThemeDB::get_singleton()->get_default_theme()->get_constant(p_item_name, edited_type));
			ur->add_undo_method(*edited_theme, "clear_constant", p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_FONT: {
			ur->add_do_method(*edited_theme, "set_font", p_item_name, edited_type, Ref<Font>());
			ur->add_undo_method(*edited_theme, "clear_font", p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_FONT_SIZE: {
			ur->add_do_method(*edited_theme, "set_font_size", p_item_name, edited_type, ThemeDB::get_singleton()->get_default_theme()->get_font_size(p_item_name, edited_type));
			ur->add_undo_method(*edited_theme, "clear_font_size", p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_ICON: {
			ur->add_do_method(*edited_theme, "set_icon", p_item_name, edited_type, Ref<Texture2D>());
			ur->add_undo_method(*edited_theme, "clear_icon", p_item_name, edited_type);
		} break;
		case Theme::DATA_TYPE_STYLEBOX: {
			Ref<StyleBox> sb;
			ur->add_do_method(*edited_theme, "set_stylebox", p_item_name, edited_type, sb);
			ur->add_undo_method(*edited_theme, "clear_stylebox", p_item_name, edited_type);
			if (is_stylebox_pinned(sb)) {
				ur->add_undo_method(this, "_unpin_leading_stylebox");
			}
		} break;
	}
	ur->commit_action();
}
void ThemeTypeEditor::_item_remove_cbk(int p_data_type, String p_item_name) {