### 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
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, false);
		child_item->set_checked(IMPORT_ITEM_DATA, false);
		child_item->propagate_check(IMPORT_ITEM, false);
		child_item->propagate_check(IMPORT_ITEM_DATA, false);
		_store_selected_item(child_item);
	}
	updating_tree = false;
}
void ThemeItemImportTree::_import_selected() {
	if (selected_items.size() == 0) {
		EditorNode::get_singleton()->show_accept(TTR("Nothing was selected for the import."), TTR("OK"));
		return;
	}
	Ref<Theme> old_snapshot = edited_theme->duplicate();
	Ref<Theme> new_snapshot = edited_theme->duplicate();
	ProgressDialog::get_singleton()->add_task("import_theme_items", TTR("Importing Theme Items"), selected_items.size() + 2);
	int idx = 0;
	for (KeyValue<ThemeItem, ItemCheckedState> &E : selected_items) {
		
		
		if (idx % 10 == 0) {
			Array arr;