Program: 1967
Project: 1967
Buggy source:
@Override public boolean onCommand(CommandSender sender,Command command,String commandLabel,String[] args){
  if (!(sender instanceof Player)) {
    sender.sendMessage(MessageUtils.mustBeIngameMessage);
    return true;
  }
  Player player=(Player)sender;
  HumanNPC npc=null;
  boolean returnval=false;
  if (NPCManager.validateSelected((Player)sender))   npc=NPCManager.get(NPCManager.selectedNPCs.get(player.getName()));
 else {
    player.sendMessage(ChatColor.RED + MessageUtils.mustHaveNPCSelectedMessage);
    return true;
  }
  if (!NPCManager.validateOwnership(player,npc.getUID())) {
    player.sendMessage(MessageUtils.notOwnerMessage);
    return true;
  }
  if (args.length == 0) {
    sender.sendMessage(ChatColor.RED + "String_Node_Str");
    return true;
  }
 else {
    if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getTrader(),Operation.TRADER_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getTrader());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getQuester(),Operation.QUESTER_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getQuester());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getHealer(),Operation.HEALER_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getHealer());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getGuard(),Operation.GUARD_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getGuard());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getWizard(),Operation.WIZARD_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getWizard());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getBlacksmith(),Operation.BLACKSMITH_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getBlacksmith());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getBandit(),Operation.BANDIT_NPC_CREATE);
        }
 else {
          toggleState(player,npc.getBandit());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args.length == 2 && args[0].equalsIgnoreCase("String_Node_Str")) {
      if (args[1].equals("String_Node_Str")) {
        toggleAll(npc,player,true);
      }
 else       if (args[1].equalsIgnoreCase("String_Node_Str")) {
        toggleAll(npc,player,false);
      }
      returnval=true;
    }
 else {
      player.sendMessage(ChatColor.RED + "String_Node_Str");
      returnval=true;
    }
  }
  PropertyManager.save(npc);
  return returnval;
}

Fixed version (ground truth):
@Override public boolean onCommand(CommandSender sender,Command command,String commandLabel,String[] args){
  if (!(sender instanceof Player)) {
    sender.sendMessage(MessageUtils.mustBeIngameMessage);
    return true;
  }
  Player player=(Player)sender;
  HumanNPC npc=null;
  boolean returnval=false;
  if (NPCManager.validateSelected((Player)sender))   npc=NPCManager.get(NPCManager.selectedNPCs.get(player.getName()));
 else {
    player.sendMessage(ChatColor.RED + MessageUtils.mustHaveNPCSelectedMessage);
    return true;
  }
  if (!NPCManager.validateOwnership(player,npc.getUID())) {
    player.sendMessage(MessageUtils.notOwnerMessage);
    return true;
  }
  if (args.length == 0) {
    sender.sendMessage(ChatColor.RED + "String_Node_Str");
    return true;
  }
 else {
    if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getTrader(),Operation.TRADER_CREATION);
        }
 else {
          toggleState(player,npc.getTrader());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getQuester(),Operation.QUESTER_CREATION);
        }
 else {
          toggleState(player,npc.getQuester());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getHealer(),Operation.HEALER_CREATION);
        }
 else {
          toggleState(player,npc.getHealer());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getGuard(),Operation.GUARD_CREATION);
        }
 else {
          toggleState(player,npc.getGuard());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getWizard(),Operation.WIZARD_CREATION);
        }
 else {
          toggleState(player,npc.getWizard());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getBlacksmith(),Operation.BLACKSMITH_CREATION);
        }
 else {
          toggleState(player,npc.getBlacksmith());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args[0].equalsIgnoreCase("String_Node_Str")) {
      if (Permission.hasPermission("String_Node_Str",sender)) {
        if (!PropertyManager.get("String_Node_Str").exists(npc)) {
          buyState(player,npc.getBandit(),Operation.BANDIT_CREATION);
        }
 else {
          toggleState(player,npc.getBandit());
        }
      }
 else {
        sender.sendMessage(MessageUtils.noPermissionsMessage);
      }
      returnval=true;
    }
 else     if (args.length == 2 && args[0].equalsIgnoreCase("String_Node_Str")) {
      if (args[1].equals("String_Node_Str")) {
        toggleAll(npc,player,true);
      }
 else       if (args[1].equalsIgnoreCase("String_Node_Str")) {
        toggleAll(npc,player,false);
      }
      returnval=true;
    }
 else {
      player.sendMessage(ChatColor.RED + "String_Node_Str");
      returnval=true;
    }
  }
  PropertyManager.save(npc);
  return returnval;
}