Class ConcurrentWaitError

A conversation tried to start a wait while another one is still pending — almost always an un-awaited c.ask() / c.retry(), or a wait started from a c.idle() callback. A conversation has a single pending-wait slot, so the newer wait is refused (the pending one keeps receiving messages). Not a control signal: in the conversation it ends through the error path (onError / bot 'error' event + errorMessage); in an idle callback it is only reported.