Program: 141603
Project: 141603
Buggy source:
@Override public void run(final CommandSender cs,String label,String[] args){
  if (!r.perm(cs,"String_Node_Str",false,true)) {
    return;
  }
  if (!r.isPlayer(cs)) {
    return;
  }
  Player p=(Player)cs;
  if (!r.checkArgs(args,0)) {
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    return;
  }
  if (args[0].equalsIgnoreCase("String_Node_Str")) {
    String message1="String_Node_Str";
    String message2="String_Node_Str";
    String message3="String_Node_Str";
    for (    MobType mob : MobType.values()) {
      if (mob.type.equals(MobType.Enemies.ENEMY)) {
        message3=message3 + "String_Node_Str" + mob.name;
      }
      if (mob.type.equals(MobType.Enemies.NEUTRAL)) {
        message2=message2 + "String_Node_Str" + mob.name;
      }
      if (mob.type.equals(MobType.Enemies.FRIENDLY)) {
        message1=message1 + "String_Node_Str" + mob.name;
      }
    }
    message1=message1.replaceFirst("String_Node_Str","String_Node_Str");
    message2=message2.replaceFirst("String_Node_Str","String_Node_Str");
    message3=message3.replaceFirst("String_Node_Str","String_Node_Str");
    r.sendMes(cs,"String_Node_Str","String_Node_Str",message3);
    r.sendMes(cs,"String_Node_Str","String_Node_Str",message2);
    r.sendMes(cs,"String_Node_Str","String_Node_Str",message1);
    return;
  }
  if (args[0].equalsIgnoreCase("String_Node_Str")) {
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    return;
  }
  Location loc=p.getLocation();
  MobType mob=MobType.fromName(args[0]);
  Integer amount=1;
  ArrayList<MobType> smob=new ArrayList<>();
  if (r.checkArgs(args,1) == true) {
    if (r.isInt(args[1])) {
      amount=Integer.parseInt(args[1]);
    }
  }
  if (mob == null || mob.name == null || mob.name.equals("String_Node_Str") || mob.getType() == null) {
    if (!args[0].contains("String_Node_Str")) {
      r.sendMes(cs,"String_Node_Str","String_Node_Str",args[0]);
      return;
    }
    ArrayList<SpawnKit> kits=new ArrayList<>();
    for (    String string : args[0].split("String_Node_Str")) {
      MobType mo1=MobType.fromName(string);
      if (mo1 == null || mo1.name == null || mo1.name.equals("String_Node_Str") || mo1.getType() == null) {
        mo1=MobType.fromName(string.split("String_Node_Str")[0]);
        if (mo1 == null || mo1.name == null || mo1.name.equals("String_Node_Str") || mo1.getType() == null) {
          r.sendMes(cs,"String_Node_Str","String_Node_Str",string);
          return;
        }
 else {
          kits.add(new SpawnKit(mo1,string.split("String_Node_Str")[1]));
        }
      }
 else {
        kits.add(new SpawnKit(mo1,"String_Node_Str"));
      }
    }
    for (int i=0; i < amount; i++) {
      LivingEntity lastmob=null;
      for (      SpawnKit kit : kits) {
        EntityType type=kit.a().getType();
        LivingEntity en=(LivingEntity)loc.getWorld().spawnEntity(loc,type);
        if (kit.a().name().equals("String_Node_Str")) {
          Skeleton skel=(Skeleton)en;
          skel.setSkeletonType(SkeletonType.WITHER);
          EntityEquipment invent=skel.getEquipment();
          invent.setItemInHand(new ItemStack(Material.STONE_SWORD,1));
          invent.setItemInHandDropChance(0.09F);
        }
 else         if (kit.a().name().equalsIgnoreCase("String_Node_Str")) {
          Skeleton skel=(Skeleton)en;
          skel.setSkeletonType(SkeletonType.NORMAL);
          skel.getEquipment().setItemInHand(new ItemStack(Material.BOW));
          skel.getEquipment().setItemInHandDropChance(0.09F);
        }
        if (kit.a().name().equalsIgnoreCase("String_Node_Str")) {
          Guardian g=(Guardian)en;
          g.setElder(true);
        }
        defaultMobData(type,en);
        if (lastmob != null) {
          lastmob.setPassenger(en);
        }
        lastmob=en;
      }
    }
    return;
  }
  for (int i=0; i < amount; i++) {
    try {
      Entity en=(Entity)loc.getWorld().spawnEntity(loc,mob.getType());
      if (args[0].equals("String_Node_Str")) {
        Skeleton skel=(Skeleton)en;
        skel.setSkeletonType(SkeletonType.WITHER);
        EntityEquipment invent=skel.getEquipment();
        invent.setItemInHand(new ItemStack(Material.STONE_SWORD,1));
        invent.setItemInHandDropChance(0.09F);
      }
      defaultMobData(mob.getType(),en);
      if (en instanceof LivingEntity) {
        utilize(args,mob,(LivingEntity)en,p);
      }
    }
 catch (    ClassCastException ex) {
      ex.printStackTrace();
    }
  }
}

Fixed version (ground truth):
@Override public void run(final CommandSender cs,String label,String[] args){
  if (!r.perm(cs,"String_Node_Str",false,true)) {
    return;
  }
  if (!r.isPlayer(cs)) {
    return;
  }
  Player p=(Player)cs;
  if (!r.checkArgs(args,0)) {
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    return;
  }
  if (args[0].equalsIgnoreCase("String_Node_Str")) {
    String message1="String_Node_Str";
    String message2="String_Node_Str";
    String message3="String_Node_Str";
    for (    MobType mob : MobType.values()) {
      if (mob.type.equals(MobType.Enemies.ENEMY)) {
        message3=message3 + "String_Node_Str" + mob.name;
      }
      if (mob.type.equals(MobType.Enemies.NEUTRAL)) {
        message2=message2 + "String_Node_Str" + mob.name;
      }
      if (mob.type.equals(MobType.Enemies.FRIENDLY)) {
        message1=message1 + "String_Node_Str" + mob.name;
      }
    }
    message1=message1.replaceFirst("String_Node_Str","String_Node_Str");
    message2=message2.replaceFirst("String_Node_Str","String_Node_Str");
    message3=message3.replaceFirst("String_Node_Str","String_Node_Str");
    r.sendMes(cs,"String_Node_Str","String_Node_Str",message3);
    r.sendMes(cs,"String_Node_Str","String_Node_Str",message2);
    r.sendMes(cs,"String_Node_Str","String_Node_Str",message1);
    return;
  }
  if (args[0].equalsIgnoreCase("String_Node_Str")) {
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    r.sendMes(cs,"String_Node_Str");
    return;
  }
  Location loc=p.getLocation();
  MobType mob=MobType.fromName(args[0]);
  Integer amount=1;
  ArrayList<MobType> smob=new ArrayList<>();
  if (r.checkArgs(args,1) == true) {
    if (r.isInt(args[1])) {
      amount=Integer.parseInt(args[1]);
    }
  }
  if (mob == null || mob.name == null || mob.name.equals("String_Node_Str") || mob.getType() == null) {
    if (!args[0].contains("String_Node_Str")) {
      r.sendMes(cs,"String_Node_Str","String_Node_Str",args[0]);
      return;
    }
    ArrayList<SpawnKit> kits=new ArrayList<>();
    for (    String string : args[0].split("String_Node_Str")) {
      MobType mo1=MobType.fromName(string);
      if (mo1 == null || mo1.name == null || mo1.name.equals("String_Node_Str") || mo1.getType() == null) {
        mo1=MobType.fromName(string.split("String_Node_Str")[0]);
        if (mo1 == null || mo1.name == null || mo1.name.equals("String_Node_Str") || mo1.getType() == null) {
          r.sendMes(cs,"String_Node_Str","String_Node_Str",string);
          return;
        }
 else {
          kits.add(new SpawnKit(mo1,string.split("String_Node_Str")[1]));
        }
      }
 else {
        kits.add(new SpawnKit(mo1,"String_Node_Str"));
      }
    }
    for (int i=0; i < amount; i++) {
      LivingEntity lastmob=null;
      for (      SpawnKit kit : kits) {
        EntityType type=kit.a().getType();
        LivingEntity en=(LivingEntity)loc.getWorld().spawnEntity(loc,type);
        if (kit.a().name().equals("String_Node_Str")) {
          Skeleton skel=(Skeleton)en;
          skel.setSkeletonType(SkeletonType.WITHER);
          EntityEquipment invent=skel.getEquipment();
          invent.setItemInHand(new ItemStack(Material.STONE_SWORD,1));
          invent.setItemInHandDropChance(0.09F);
        }
 else         if (kit.a().name().equalsIgnoreCase("String_Node_Str")) {
          Skeleton skel=(Skeleton)en;
          skel.setSkeletonType(SkeletonType.NORMAL);
          skel.getEquipment().setItemInHand(new ItemStack(Material.BOW));
          skel.getEquipment().setItemInHandDropChance(0.09F);
        }
        if (kit.a().name().equalsIgnoreCase("String_Node_Str")) {
          Guardian g=(Guardian)en;
          g.setElder(true);
        }
        defaultMobData(type,en);
        if (lastmob != null) {
          lastmob.setPassenger(en);
        }
        lastmob=en;
      }
    }
    return;
  }
  for (int i=0; i < amount; i++) {
    try {
      Entity en=loc.getWorld().spawnEntity(loc,mob.getType());
      if (args[0].equals("String_Node_Str")) {
        Skeleton skel=(Skeleton)en;
        skel.setSkeletonType(SkeletonType.WITHER);
        EntityEquipment invent=skel.getEquipment();
        invent.setItemInHand(new ItemStack(Material.STONE_SWORD,1));
        invent.setItemInHandDropChance(0.09F);
      }
      defaultMobData(mob.getType(),en);
      if (en instanceof LivingEntity) {
        utilize(args,mob,(LivingEntity)en,p);
      }
    }
 catch (    ClassCastException ex) {
      ex.printStackTrace();
    }
  }
}