How-to add new nodes in a TreeStore/REST with error handling?

.appendChild() works great but don't have any callback method so there are no way of handling backend api errors.

Creating a new node from the model and do a .save() on it gives me the callback but requires the store to be reloaded, i.e. not as neat solution as inserting directly into the story and letting it sync the changes to the backend.

There must be a way of inserting directly with error handling?

How-to add new nodes in a TreeStore/REST with error handling?