Ensure victim is a user to avoid crashing (#40)

src/mod/irc.mod/mode.c

@@ -721,7 +721,7 @@ got_deop(struct chanset_t *chan, memberlist *m, memberlist *mv, char *isserver)
       putlog(LOG_MODES, chan->dname, "TS resync deopped me on %s :(", chan->dname);
   } else {
     // Revenge kick clients that deop our bots
-    if (chan->revenge && m && mv->user->bot) {
+    if (chan->revenge && m && mv->user && mv->user->bot) {
       if (role < 5 && !chan_sentkick(m) && me_op(chan)) {
         m->flags |= SENTKICK;
         dprintf(DP_MODE_NEXT, "KICK %s %s :%s%s\r\n", chan->name, m->nick, kickprefix, response(RES_REVENGE));