Core(fix): correct nick generation

Author: SilverRainZ

src/core/app_irc_event.c

@@ -1378,13 +1378,13 @@ static void irc_event_numeric(SircSession *sirc, int event,
                 if (!srv->registered){
                     char *new_nick;
 
-                    if (strlen(nick) - strlen(srv->user->nick) >= 2) {
+                    if (strlen(nick) - strlen(srv->cfg->user->nick) <= 2) {
                         // Try new nick with a trailing underline('_')
                         new_nick = g_strdup_printf("%s_", nick);
                     } else {
                         // Rewind to original nickname when there are too much
                         // trailing underlines
-                        new_nick = g_strdup(srv->user->nick);
+                        new_nick = g_strdup(srv->cfg->user->nick);
                     }
 
                     // FIXME: ircd-seven will truncate the nick without