FIX: slave: nil pointer dereference if slave is unreachable
FIX: slave: nil pointer dereference if slave is unreachable

If the session cant be opened it is nil and session.Close() crashes

KIT-MAMID/mamid,KIT-MAMID/mamid,KIT-MAMID/mamid,KIT-MAMID/mamid,KIT-MAMID/mamid