PureSocketClusterSocket.Subscribe Ack is never used/dropped

[raplemie]

PureSocketClusterSocket.Subscribe allow for an "Ack" method to be provided, however acks for Subscribe are only {rid:"3"} with no data, so the messages are not handled because of the condition below in private void Socket_OnMessage(object sender, string messge) function:

This makes 2 things happens, the _acks are never called, but also never cleaned. I did not check if other event had the same issue.