Program: 51682
Project: 51682
Buggy source:
public void simpleMode(InventoryClickEvent event,TraderStatus trader,StockItem si,InventoryTrait sr){
  if (event.getWhoClicked() instanceof Player) {
    Player p=(Player)event.getWhoClicked();
    DecimalFormat f=new DecimalFormat("String_Node_Str");
    boolean top=event.getView().convertSlot(event.getRawSlot()) == event.getRawSlot();
    if ((trader.getStatus().equals(Status.PLAYER_SELL) || trader.getStatus().equals(Status.PLAYER_SELL_AMOUT))) {
      if (top) {
        if (trader.getStatus().equals(Status.PLAYER_SELL_AMOUT))         si=trader.getStockItem();
 else         si=sr.itemForSell(event.getSlot());
        if (si != null) {
          if (trader.getStatus().equals(Status.PLAYER_SELL_AMOUT)) {
            if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
              trader.getInventory().clear();
              sr.inventoryView(trader.getInventory(),Status.PLAYER_SELL);
              trader.setStatus(Status.PLAYER_SELL);
              trader.setStockItem(null);
            }
 else {
              if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
                if (trader.getLastSlot() != event.getSlot()) {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice(event.getSlot()))+ "String_Node_Str");
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                  trader.setLastSlot(event.getSlot());
                }
 else {
                  if (econ.has(p.getName(),si.getPrice(event.getSlot()))) {
                    econ.withdrawPlayer(p.getName(),si.getPrice(event.getSlot()));
                    p.getInventory().addItem(event.getCurrentItem());
                    p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCurrentItem().getAmount()+ "String_Node_Str"+ f.format(si.getPrice(event.getSlot()))+ "String_Node_Str");
                    trader.setLastSlot(-1);
                  }
 else {
                    p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                    trader.setLastSlot(-1);
                  }
                }
              }
            }
          }
 else           if (trader.getStatus().equals(Status.PLAYER_SELL)) {
            if (si.hasMultipleAmouts()) {
              if (trader.getStatus().equals(Status.PLAYER_SELL)) {
                trader.getInventory().clear();
                InventoryTrait.setInventoryWith(trader.getInventory(),si);
                trader.setStatus(Status.PLAYER_SELL_AMOUT);
                trader.setStockItem(si);
              }
            }
 else {
              if (trader.getLastSlot() != event.getSlot()) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice())+ "String_Node_Str");
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                trader.setLastSlot(event.getSlot());
              }
 else {
                if (econ.has(p.getName(),si.getPrice()) && trader.getLastInv()) {
                  econ.withdrawPlayer(p.getName(),si.getPrice());
                  p.getInventory().addItem(si.getItemStack());
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getItemStack().getAmount()+ "String_Node_Str"+ f.format(si.getPrice())+ "String_Node_Str");
                  trader.setLastSlot(-1);
                }
 else {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                  trader.setLastSlot(-1);
                }
              }
            }
          }
        }
 else         if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
          trader.getInventory().clear();
          sr.inventoryView(trader.getInventory(),Status.PLAYER_BUY);
          trader.setStatus(Status.PLAYER_BUY);
          trader.setStockItem(null);
        }
        trader.setLastInv(true);
      }
 else {
        si=sr.wantItemBuy(event.getCurrentItem());
        if (si != null) {
          if (trader.getLastSlot() == event.getSlot() && !trader.getLastInv()) {
            econ.depositPlayer(p.getName(),si.getPrice() * event.getCurrentItem().getAmount());
            p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCurrentItem().getAmount()+ "String_Node_Str"+ f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
            event.setCurrentItem(new ItemStack(Material.AIR));
            trader.setLastSlot(-1);
          }
 else {
            if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
              p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
              p.sendMessage(ChatColor.GOLD + "String_Node_Str");
              trader.setLastSlot(event.getSlot());
            }
          }
        }
        trader.setLastInv(false);
      }
    }
 else     if (trader.getStatus().equals(Status.PLAYER_BUY)) {
      if (top) {
        if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
          trader.getInventory().clear();
          sr.inventoryView(trader.getInventory(),Status.PLAYER_SELL);
          trader.setStatus(Status.PLAYER_SELL);
          trader.setStockItem(null);
        }
 else {
          p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
        }
      }
 else {
        si=sr.wantItemBuy(event.getCurrentItem());
        if (si != null) {
          if (trader.getLastSlot() == event.getSlot()) {
            econ.depositPlayer(p.getName(),si.getPrice() * event.getCurrentItem().getAmount());
            p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCurrentItem().getAmount()+ "String_Node_Str"+ f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
            event.setCurrentItem(new ItemStack(Material.AIR));
            trader.setLastSlot(-1);
          }
 else {
            if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
              p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
              p.sendMessage(ChatColor.GOLD + "String_Node_Str");
              trader.setLastSlot(event.getSlot());
            }
          }
        }
      }
    }
  }
}

Fixed version (ground truth):
public void simpleMode(InventoryClickEvent event,TraderStatus trader,StockItem si,InventoryTrait sr){
  if (event.getWhoClicked() instanceof Player) {
    Player p=(Player)event.getWhoClicked();
    DecimalFormat f=new DecimalFormat("String_Node_Str");
    boolean top=event.getView().convertSlot(event.getRawSlot()) == event.getRawSlot();
    if ((trader.getStatus().equals(Status.PLAYER_SELL) || trader.getStatus().equals(Status.PLAYER_SELL_AMOUT))) {
      if (top) {
        if (trader.getStatus().equals(Status.PLAYER_SELL_AMOUT))         si=trader.getStockItem();
 else         si=sr.itemForSell(event.getSlot());
        if (si != null) {
          if (trader.getStatus().equals(Status.PLAYER_SELL_AMOUT)) {
            if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
              trader.getInventory().clear();
              sr.inventoryView(trader.getInventory(),Status.PLAYER_SELL);
              trader.setStatus(Status.PLAYER_SELL);
              trader.setStockItem(null);
            }
 else {
              if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
                if (trader.getLastSlot() != event.getSlot()) {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice(event.getSlot()))+ "String_Node_Str");
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                  trader.setLastSlot(event.getSlot());
                }
 else {
                  if (econ.has(p.getName(),si.getPrice(event.getSlot()))) {
                    econ.withdrawPlayer(p.getName(),si.getPrice(event.getSlot()));
                    p.getInventory().addItem(event.getCurrentItem());
                    p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCurrentItem().getAmount()+ "String_Node_Str"+ f.format(si.getPrice(event.getSlot()))+ "String_Node_Str");
                    trader.setLastSlot(-1);
                  }
 else {
                    p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                    trader.setLastSlot(-1);
                  }
                }
              }
            }
          }
 else           if (trader.getStatus().equals(Status.PLAYER_SELL)) {
            if (si.hasMultipleAmouts()) {
              if (trader.getStatus().equals(Status.PLAYER_SELL)) {
                trader.getInventory().clear();
                InventoryTrait.setInventoryWith(trader.getInventory(),si);
                trader.setStatus(Status.PLAYER_SELL_AMOUT);
                trader.setStockItem(si);
              }
            }
 else {
              if (trader.getLastSlot() != event.getSlot()) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice())+ "String_Node_Str");
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                trader.setLastSlot(event.getSlot());
              }
 else {
                if (econ.has(p.getName(),si.getPrice()) && trader.getLastInv()) {
                  econ.withdrawPlayer(p.getName(),si.getPrice());
                  p.getInventory().addItem(si.getItemStack());
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getItemStack().getAmount()+ "String_Node_Str"+ f.format(si.getPrice())+ "String_Node_Str");
                  trader.setLastSlot(-1);
                }
 else {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                  trader.setLastSlot(-1);
                }
              }
            }
          }
        }
 else         if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)5)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
          trader.getInventory().clear();
          sr.inventoryView(trader.getInventory(),Status.PLAYER_BUY);
          trader.setStatus(Status.PLAYER_BUY);
          trader.setStockItem(null);
        }
        trader.setLastInv(true);
      }
 else {
        si=sr.wantItemBuy(event.getCurrentItem());
        if (si != null) {
          if (trader.getLastSlot() == event.getSlot() && !trader.getLastInv()) {
            econ.depositPlayer(p.getName(),si.getPrice() * event.getCurrentItem().getAmount());
            p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCurrentItem().getAmount()+ "String_Node_Str"+ f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
            event.setCurrentItem(new ItemStack(Material.AIR));
            trader.setLastSlot(-1);
          }
 else {
            if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
              p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
              p.sendMessage(ChatColor.GOLD + "String_Node_Str");
              trader.setLastSlot(event.getSlot());
            }
          }
        }
        trader.setLastInv(false);
      }
    }
 else     if (trader.getStatus().equals(Status.PLAYER_BUY)) {
      if (top) {
        si=sr.wantItemBuy(event.getSlot());
        if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && (event.getSlot() == trader.getInventory().getSize() - 1)) {
          trader.getInventory().clear();
          sr.inventoryView(trader.getInventory(),Status.PLAYER_SELL);
          trader.setStatus(Status.PLAYER_SELL);
          trader.setStockItem(null);
        }
 else {
          if (si != null)           p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
        }
        event.setCancelled(true);
      }
 else {
        si=sr.wantItemBuy(event.getCurrentItem());
        if (si != null) {
          if (trader.getLastSlot() == event.getSlot()) {
            econ.depositPlayer(p.getName(),si.getPrice() * event.getCurrentItem().getAmount());
            p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCurrentItem().getAmount()+ "String_Node_Str"+ f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
            event.setCurrentItem(new ItemStack(Material.AIR));
            trader.setLastSlot(-1);
          }
 else {
            if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)3)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
              p.sendMessage(ChatColor.GOLD + "String_Node_Str" + f.format(si.getPrice() * event.getCurrentItem().getAmount())+ "String_Node_Str");
              p.sendMessage(ChatColor.GOLD + "String_Node_Str");
              trader.setLastSlot(event.getSlot());
            }
          }
        }
      }
    }
  }
}