The author apologises for an error in Lemma 3.1, which does not show that the limit lies in the unit ball, so it cannot be concluded that the unit ball is compact for this topology.
This lemma was needed for all the results in Section 3. In particular, the proof that the predual of Lip0 (X) is unique when X is a Banach space fails. Theorem 2.4 and 3.3 remain valid.