Program: 25109
Project: 25109
Buggy source:
public static int prefix(Player player,String[] args){
  if (player.canUseCommand("String_Node_Str")) {
    if (args.length < 2) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      player.sendMessage(Colors.DarkPurple + "String_Node_Str" + player.getName()+ "String_Node_Str");
      vMinecraftChat.sendMessage(player,player,Colors.DarkPurple + "String_Node_Str" + Colors.Black+ "String_Node_Str"+ Colors.LightGreen+ "String_Node_Str"+ Colors.Black+ "String_Node_Str"+ Colors.Yellow+ player.getName());
      return EXIT_SUCCESS;
    }
    if (args[1].length() > 15) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      return EXIT_SUCCESS;
    }
    Player other=etc.getServer().matchPlayer(args[0]);
    if (other == null) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      return EXIT_SUCCESS;
    }
    if (args.length >= 2 && args[0] != null) {
      player.setPrefix(args[1]);
    }
    if (args.length >= 3 && args[1] != null) {
      vMinecraftUsers.players.findProfile(player).setTag(args[2]);
    }
    return EXIT_SUCCESS;
  }
  if (!player.canUseCommand("String_Node_Str")) {
    return EXIT_FAIL;
  }
  if (args.length < 1) {
    vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
    player.sendMessage(Colors.DarkPurple + "String_Node_Str");
    vMinecraftChat.sendMessage(player,player,Colors.DarkPurple + "String_Node_Str" + Colors.Black+ "String_Node_Str"+ Colors.LightGreen+ "String_Node_Str"+ Colors.Black+ "String_Node_Str"+ Colors.Yellow+ player.getName());
    return EXIT_SUCCESS;
  }
  if (args[1].length() > 15) {
    vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
    return EXIT_SUCCESS;
  }
  if (args.length >= 1 && args[0] != null) {
    player.setPrefix(args[1]);
  }
  if (args.length >= 2 && args[1] != null) {
    vMinecraftUsers.players.findProfile(player).setTag(args[2]);
  }
  return EXIT_SUCCESS;
}

Fixed version (ground truth):
public static int prefix(Player player,String[] args){
  if (player.canUseCommand("String_Node_Str")) {
    if (args.length < 2) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      player.sendMessage(Colors.DarkPurple + "String_Node_Str" + player.getName()+ "String_Node_Str");
      vMinecraftChat.sendMessage(player,player,Colors.DarkPurple + "String_Node_Str" + Colors.Black+ "String_Node_Str"+ Colors.LightGreen+ "String_Node_Str"+ Colors.Black+ "String_Node_Str"+ Colors.Yellow+ player.getName());
      return EXIT_SUCCESS;
    }
    if (args[1].length() > 15) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      return EXIT_SUCCESS;
    }
    Player other=etc.getServer().matchPlayer(args[0]);
    if (other == null) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      return EXIT_SUCCESS;
    }
    if (args.length >= 2 && args[0] != null) {
      player.setPrefix(args[1]);
    }
    if (args.length >= 3 && args[1] != null) {
      vMinecraftUsers.players.findProfile(player).setTag(args[2]);
    }
    return EXIT_SUCCESS;
  }
  if (!player.canUseCommand("String_Node_Str")) {
    return EXIT_FAIL;
  }
  if (args.length < 1) {
    vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
    player.sendMessage(Colors.DarkPurple + "String_Node_Str");
    vMinecraftChat.sendMessage(player,player,Colors.DarkPurple + "String_Node_Str" + Colors.Black+ "String_Node_Str"+ Colors.LightGreen+ "String_Node_Str"+ Colors.Black+ "String_Node_Str"+ Colors.Yellow+ player.getName());
    return EXIT_SUCCESS;
  }
  if (args.length >= 1 && args[0] != null) {
    player.setPrefix(args[0]);
    player.sendMessage(Colors.Rose + "String_Node_Str");
  }
  if (args.length >= 2 && args[1] != null) {
    if (args[1].length() > 15) {
      vMinecraftChat.sendMessage(player,player,Colors.Rose + "String_Node_Str");
      return EXIT_SUCCESS;
    }
    vMinecraftUsers.players.findProfile(player).setTag(args[1]);
    player.sendMessage(Colors.LightGreen + "String_Node_Str");
  }
  return EXIT_SUCCESS;
}