Program: 109373
Project: 109373
Buggy source:
@Override public void onTick(){
  if (!bot.hasSpawned() || !bot.isConnected())   return;
  if (ticksToGo > 0) {
    ticksToGo--;
    return;
  }
  MainPlayerEntity player=bot.getPlayer();
  if (player == null)   return;
  if (firstStart) {
    bot.say("String_Node_Str");
    try {
      Thread.sleep(500);
    }
 catch (    InterruptedException e) {
      e.printStackTrace();
    }
    connectionHandler.sendPacket(new Packet255KickDisconnect("String_Node_Str"));
    ticksToGo=15;
    firstStart=false;
    return;
  }
 else   canSpam=true;
  if (canSpam) {
    if (die) {
      connectionHandler.sendPacket(new Packet255KickDisconnect("String_Node_Str"));
      ticksToGo=15;
      return;
    }
    if (!bot.hasSpawned())     return;
    if (spamMessage == null)     return;
    if (nextMessage > 0) {
      nextMessage--;
      return;
    }
    String message=spamMessage;
    MessageFormatter formatter=new MessageFormatter();
    String botName;
synchronized (bots) {
      botName=bots.get(nextBot++).bot.getSession().getUsername();
      if (nextBot >= bots.size())       nextBot=0;
    }
    formatter.setVariable("String_Node_Str",botName);
    if (spamList.length > 0) {
      formatter.setVariable("String_Node_Str",spamList[nextSpamList++]);
      if (nextSpamList >= spamList.length)       nextSpamList=0;
    }
    formatter.setVariable("String_Node_Str",Util.generateRandomString(15 + random.nextInt(6)));
    formatter.setVariable("String_Node_Str",Character.toString(msgChars[nextMsgChar++]));
    if (nextMsgChar >= msgChars.length)     nextMsgChar=0;
    message=formatter.format(message);
    connectionHandler.sendPacket(new Packet3Chat(message));
  }
}

Fixed version (ground truth):
@EventHandler public void onTick(TickEvent event){
  if (!bot.hasSpawned() || !bot.isConnected())   return;
  if (ticksToGo > 0) {
    ticksToGo--;
    return;
  }
  MainPlayerEntity player=bot.getPlayer();
  if (player == null)   return;
  if (firstStart) {
    bot.say("String_Node_Str");
    try {
      Thread.sleep(500);
    }
 catch (    InterruptedException e) {
      e.printStackTrace();
    }
    connectionHandler.sendPacket(new Packet255KickDisconnect("String_Node_Str"));
    ticksToGo=15;
    firstStart=false;
    return;
  }
 else   canSpam=true;
  if (canSpam) {
    if (die) {
      connectionHandler.sendPacket(new Packet255KickDisconnect("String_Node_Str"));
      ticksToGo=15;
      return;
    }
    if (!bot.hasSpawned())     return;
    if (spamMessage == null)     return;
    if (nextMessage > 0) {
      nextMessage--;
      return;
    }
    String message=spamMessage;
    MessageFormatter formatter=new MessageFormatter();
    String botName;
synchronized (bots) {
      botName=bots.get(nextBot++).bot.getSession().getUsername();
      if (nextBot >= bots.size())       nextBot=0;
    }
    formatter.setVariable("String_Node_Str",botName);
    if (spamList.length > 0) {
      formatter.setVariable("String_Node_Str",spamList[nextSpamList++]);
      if (nextSpamList >= spamList.length)       nextSpamList=0;
    }
    formatter.setVariable("String_Node_Str",Util.generateRandomString(15 + random.nextInt(6)));
    formatter.setVariable("String_Node_Str",Character.toString(msgChars[nextMsgChar++]));
    if (nextMsgChar >= msgChars.length)     nextMsgChar=0;
    message=formatter.format(message);
    connectionHandler.sendPacket(new Packet3Chat(message));
  }
}