### 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
break;
		case Theme::DATA_TYPE_MAX:
			return; 
	}
	updating_tree = true;
	for (List<TreeItem *>::Element *E = item_list->front(); E; E = E->next()) {
		TreeItem *child_item = E->get();
		if (!child_item) {
			continue;
		}
		child_item->set_checked(IMPORT_ITEM, true);
		child_item->propagate_check(IMPORT_ITEM, false);
		_store_selected_item(child_item);
	}
	updating_tree = false;
}
void ThemeItemImportTree::_select_full_data_type_pressed(int p_data_type) {
	ERR_FAIL_INDEX_MSG(p_data_type, Theme::DATA_TYPE_MAX, "Theme item data type is out of bounds.");
	if (updating_tree) {
		return;
	}
	Theme::DataType data_type = (Theme::DataType)p_data_type;
	List<TreeItem *> *item_list = nullptr;
	switch (data_type) {
		case Theme::DATA_TYPE_COLOR:
			item_list = &tree_color_items;
			break;
		case Theme::DATA_TYPE_CONSTANT:
			item_list = &tree_constant_items;
			break;