If backend fails and sets session state to SESSION_STATE_STOPPING before session is in state SESSION_STATE_ROUTER_READY, sessoin.c:session_alloc overwrites the session state by SESSION_STATE_ROUTER_READY. Protected session state modification and added check before changing the state.

cloesSession was called in session.c:session_free if all DCBs had been removed their references to session. closeSession, however, is function which handles closing router. Router is responsible for closing all backend DCBs (=connections). Thus, calling sessionClose after all backend connections had been removed already is unnecessary and causes assertion traps.

Simply removed the call.