CEP-15 (Accord) NPE in accord.topology.TopologyManager.localForEpoch

java.lang.NullPointerException
	at accord.topology.TopologyManager.localForEpoch(TopologyManager.java:402)
	at accord.local.Node.trySelectProgressKey(Node.java:431)
	at accord.messages.TxnRequest.progressKey(TxnRequest.java:151)
	at accord.messages.TxnRequest.process(TxnRequest.java:143)
	at org.apache.cassandra.service.accord.AccordVerbHandler.doVerb(AccordVerbHandler.java:46)

private EpochState get(long epoch)
{
    if (epoch > currentEpoch || epoch <= currentEpoch - epochs.length)
        return null;

    return epochs[(int) (currentEpoch - epoch)];
}