Program: 51618
Project: 51618
Buggy source:
@EventHandler public void onNPCRightCLick(NPCRightClickEvent event){
  if (!isEconomyNpc(event.getNPC()))   return;
  CitizensTrader.getInstance();
  if (CitizensTrader.getDenizen() != null && CitizensTrader.getDenizen().getDenizenNPCRegistry().isDenizenNPC(event.getNPC()))   return;
  Player player=event.getClicker();
  final String playerName=player.getName();
  NPC npc=event.getNPC();
  EconomyNpc economyNpc=playerInteraction.get(playerName);
  TraderCharacterTrait characterTrait=npc.getTrait(TraderCharacterTrait.class);
switch (characterTrait.getType()) {
case SERVER_TRADER:
{
      if (economyNpc != null) {
        if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
          player.sendMessage(locale.getLocaleString("String_Node_Str"));
          return;
        }
        if (economyNpc.getNpcId() == npc.getId()) {
          economyNpc.onRightClick(player,characterTrait,npc);
          if (!economyNpc.locked())           playerInteraction.remove(playerName);
        }
 else {
          player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
          EconomyNpc newNpc=new ServerTrader(characterTrait,npc,player);
          ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
          playerInteraction.put(playerName,newNpc);
          if (!newNpc.onRightClick(player,characterTrait,npc))           playerInteraction.remove(playerName);
        }
      }
 else {
        EconomyNpc newNpc=new ServerTrader(characterTrait,npc,player);
        playerInteraction.put(playerName,newNpc);
        if (!newNpc.onRightClick(player,characterTrait,npc))         playerInteraction.remove(playerName);
      }
      return;
    }
case PLAYER_TRADER:
{
    if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
      player.sendMessage(locale.getLocaleString("String_Node_Str"));
      return;
    }
    if (economyNpc != null) {
      if (economyNpc.getNpcId() == npc.getId()) {
        economyNpc.onRightClick(player,characterTrait,npc);
        if (!economyNpc.locked())         playerInteraction.remove(playerName);
      }
 else {
        player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
        EconomyNpc newNpc=new PlayerTrader(characterTrait,npc,player);
        ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
        playerInteraction.put(playerName,newNpc);
        if (!newNpc.onRightClick(player,characterTrait,npc))         playerInteraction.remove(playerName);
      }
    }
 else {
      EconomyNpc newNpc=new PlayerTrader(characterTrait,npc,player);
      ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
      playerInteraction.put(playerName,newNpc);
      if (!newNpc.onRightClick(player,characterTrait,npc))       playerInteraction.remove(playerName);
    }
    return;
  }
case MARKET_TRADER:
{
  if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
    player.sendMessage(locale.getLocaleString("String_Node_Str"));
    return;
  }
  if (economyNpc != null) {
    if (economyNpc.getNpcId() == npc.getId()) {
      economyNpc.onRightClick(player,characterTrait,npc);
      if (!economyNpc.locked())       playerInteraction.remove(playerName);
    }
 else {
      player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
      EconomyNpc newNpc=new MarketTrader(characterTrait,npc,player);
      ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
      playerInteraction.put(playerName,newNpc);
      if (!newNpc.onRightClick(player,characterTrait,npc))       playerInteraction.remove(playerName);
    }
  }
 else {
    EconomyNpc newNpc=new MarketTrader(characterTrait,npc,player);
    ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
    playerInteraction.put(playerName,newNpc);
    if (!newNpc.onRightClick(player,characterTrait,npc))     playerInteraction.remove(playerName);
  }
  return;
}
case PRIVATE_BANKER:
{
if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
  player.sendMessage(locale.getLocaleString("String_Node_Str"));
  return;
}
if (economyNpc != null) {
  if (economyNpc.getNpcId() == npc.getId()) {
    economyNpc.onRightClick(player,characterTrait,npc);
    if (!economyNpc.locked())     playerInteraction.remove(playerName);
  }
 else {
    player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
    EconomyNpc newNpc=new PlayerBanker(npc,characterTrait.getBankTrait(),playerName);
    Banker banker=(Banker)playerInteraction.get(playerName);
    if (!Banker.hasAccount(player)) {
      playerInteraction.remove(playerName);
      return;
    }
    playerInteraction.put(playerName,newNpc);
    player.sendMessage(locale.getLocaleString("String_Node_Str").replace("String_Node_Str",new DecimalFormat("String_Node_Str").format(banker.getDepositFee())));
    player.sendMessage(locale.getLocaleString("String_Node_Str").replace("String_Node_Str",new DecimalFormat("String_Node_Str").format(banker.getWithdrawFee())));
    newNpc.onRightClick(player,characterTrait,npc);
  }
}
 else {
  if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
    player.sendMessage(locale.getLocaleString("String_Node_Str"));
    return;
  }
  EconomyNpc newNpc=new PlayerBanker(npc,characterTrait.getBankTrait(),playerName);
  if (!Banker.hasAccount(player)) {
    playerInteraction.remove(playerName);
    return;
  }
  playerInteraction.put(playerName,newNpc);
  newNpc.onRightClick(player,characterTrait,npc);
}
return;
}
case MONEY_BANKER:
{
if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
player.sendMessage(locale.getLocaleString("String_Node_Str"));
return;
}
if (economyNpc != null) {
{
  player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
  EconomyNpc newNpc=new MoneyBanker(npc,characterTrait.getBankTrait(),playerName);
  playerInteraction.put(playerName,newNpc);
  newNpc.onRightClick(player,characterTrait,npc);
}
}
 else {
EconomyNpc newNpc=new MoneyBanker(npc,characterTrait.getBankTrait(),playerName);
playerInteraction.put(playerName,newNpc);
newNpc.onRightClick(player,characterTrait,npc);
}
return;
}
default :
{
}
}
}

Fixed version (ground truth):
@EventHandler public void onNPCRightCLick(NPCRightClickEvent event){
  if (!isEconomyNpc(event.getNPC()))   return;
  CitizensTrader.getInstance();
  if (CitizensTrader.getDenizen() != null && CitizensTrader.getDenizen().getDenizenNPCRegistry().isDenizenNPC(event.getNPC()))   return;
  Player player=event.getClicker();
  final String playerName=player.getName();
  NPC npc=event.getNPC();
  EconomyNpc economyNpc=playerInteraction.get(playerName);
  TraderCharacterTrait characterTrait=npc.getTrait(TraderCharacterTrait.class);
switch (characterTrait.getType()) {
case SERVER_TRADER:
{
      if (economyNpc != null) {
        if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
          player.sendMessage(locale.getLocaleString("String_Node_Str"));
          return;
        }
        if (economyNpc.getNpcId() == npc.getId()) {
          economyNpc.onRightClick(player,characterTrait,npc);
          if (!economyNpc.locked())           playerInteraction.remove(playerName);
        }
 else {
          player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
          EconomyNpc newNpc=new ServerTrader(characterTrait,npc,player);
          ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
          playerInteraction.put(playerName,newNpc);
          if (!newNpc.onRightClick(player,characterTrait,npc))           playerInteraction.remove(playerName);
        }
      }
 else {
        EconomyNpc newNpc=new ServerTrader(characterTrait,npc,player);
        playerInteraction.put(playerName,newNpc);
        if (!newNpc.onRightClick(player,characterTrait,npc))         playerInteraction.remove(playerName);
      }
      return;
    }
case PLAYER_TRADER:
{
    if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
      player.sendMessage(locale.getLocaleString("String_Node_Str"));
      return;
    }
    if (economyNpc != null) {
      if (economyNpc.getNpcId() == npc.getId()) {
        economyNpc.onRightClick(player,characterTrait,npc);
        if (!economyNpc.locked())         playerInteraction.remove(playerName);
      }
 else {
        player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
        EconomyNpc newNpc=new PlayerTrader(characterTrait,npc,player);
        ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
        playerInteraction.put(playerName,newNpc);
        if (!newNpc.onRightClick(player,characterTrait,npc))         playerInteraction.remove(playerName);
      }
    }
 else {
      EconomyNpc newNpc=new PlayerTrader(characterTrait,npc,player);
      ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
      playerInteraction.put(playerName,newNpc);
      if (!newNpc.onRightClick(player,characterTrait,npc))       playerInteraction.remove(playerName);
    }
    return;
  }
case MARKET_TRADER:
{
  if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
    player.sendMessage(locale.getLocaleString("String_Node_Str"));
    return;
  }
  if (economyNpc != null) {
    if (economyNpc.getNpcId() == npc.getId()) {
      economyNpc.onRightClick(player,characterTrait,npc);
      if (!economyNpc.locked())       playerInteraction.remove(playerName);
    }
 else {
      player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
      EconomyNpc newNpc=new MarketTrader(characterTrait,npc,player);
      ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
      playerInteraction.put(playerName,newNpc);
      if (!newNpc.onRightClick(player,characterTrait,npc))       playerInteraction.remove(playerName);
    }
  }
 else {
    EconomyNpc newNpc=new MarketTrader(characterTrait,npc,player);
    ((Trader)newNpc).switchInventory(Trader.getStartStatus(player));
    playerInteraction.put(playerName,newNpc);
    if (!newNpc.onRightClick(player,characterTrait,npc))     playerInteraction.remove(playerName);
  }
  return;
}
case PRIVATE_BANKER:
{
if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
  player.sendMessage(locale.getLocaleString("String_Node_Str"));
  return;
}
if (economyNpc != null) {
  if (economyNpc.getNpcId() == npc.getId()) {
    economyNpc.onRightClick(player,characterTrait,npc);
    if (!economyNpc.locked())     playerInteraction.remove(playerName);
  }
 else {
    player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
    EconomyNpc newNpc=new PrivateBanker(npc,characterTrait.getBankTrait(),playerName);
    Banker banker=(Banker)playerInteraction.get(playerName);
    if (!Banker.hasAccount(player)) {
      playerInteraction.remove(playerName);
      return;
    }
    playerInteraction.put(playerName,newNpc);
    player.sendMessage(locale.getLocaleString("String_Node_Str").replace("String_Node_Str",new DecimalFormat("String_Node_Str").format(banker.getDepositFee())));
    player.sendMessage(locale.getLocaleString("String_Node_Str").replace("String_Node_Str",new DecimalFormat("String_Node_Str").format(banker.getWithdrawFee())));
    newNpc.onRightClick(player,characterTrait,npc);
  }
}
 else {
  if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
    player.sendMessage(locale.getLocaleString("String_Node_Str"));
    return;
  }
  EconomyNpc newNpc=new PrivateBanker(npc,characterTrait.getBankTrait(),playerName);
  if (!Banker.hasAccount(player)) {
    playerInteraction.remove(playerName);
    return;
  }
  playerInteraction.put(playerName,newNpc);
  newNpc.onRightClick(player,characterTrait,npc);
}
return;
}
case MONEY_BANKER:
{
if (!permManager.has(player,"String_Node_Str" + characterTrait.getType().toString())) {
player.sendMessage(locale.getLocaleString("String_Node_Str"));
return;
}
if (economyNpc != null) {
{
  player.sendMessage(ChatColor.AQUA + economyNpc.getNpc().getFullName() + ChatColor.RED+ "String_Node_Str");
  EconomyNpc newNpc=new MoneyBanker(npc,characterTrait.getBankTrait(),playerName);
  playerInteraction.put(playerName,newNpc);
  newNpc.onRightClick(player,characterTrait,npc);
}
}
 else {
EconomyNpc newNpc=new MoneyBanker(npc,characterTrait.getBankTrait(),playerName);
playerInteraction.put(playerName,newNpc);
newNpc.onRightClick(player,characterTrait,npc);
}
return;
}
default :
{
}
}
}