Thanx for this clarification of a use case. :)

IMHO again this could be solved with a coderef wrapper $c_parent which calls the real method only on definedness of the object.

 $node->$c_parent->$c_parent

Another (classical) approach would be defining a NULL-node object which is returned instead of undef and wouldn't cause an error.

But the latter would only work if one has access to the design of underlying library.