Program: 51692
Project: 51692
Buggy source:
@EventHandler public void inventoryClick(InventoryClickEvent event){
  if (event.getRawSlot() < 0)   return;
  if (event.getWhoClicked() instanceof Player) {
    Player p=(Player)event.getWhoClicked();
    if (state.containsKey(p.getName())) {
      TraderStatus trader=state.get(p.getName());
      InventoryTrait sr=trader.getTrader().getTrait(InventoryTrait.class);
      boolean top=event.getView().convertSlot(event.getRawSlot()) == event.getRawSlot();
      if ((!trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) && !trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) && !trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE) && top) {
        StockItem si=null;
        if (trader.getStatus().equals(Status.PLAYER_SELL) || trader.getStatus().equals(Status.PLAYER_SELL_AMOUT)) {
          if (trader.getStatus().equals(Status.PLAYER_SELL_AMOUT))           si=trader.getStockItem();
 else           si=sr.itemForSell(event.getSlot());
          if (si != null) {
            if (event.isShiftClick()) {
              if (si.hasMultipleAmouts() && trader.getStatus().equals(Status.PLAYER_SELL_AMOUT)) {
                if (econ.has(p.getName(),si.getPrice(event.getSlot()))) {
                  if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
                    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"+ si.getPrice(event.getSlot())+ "String_Node_Str");
                  }
                }
 else {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                }
              }
 else {
                if (econ.has(p.getName(),si.getPrice())) {
                  econ.withdrawPlayer(p.getName(),si.getPrice());
                  p.getInventory().addItem(si.getItemStack());
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getItemStack().getAmount()+ "String_Node_Str"+ si.getPrice()+ "String_Node_Str");
                }
 else {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                }
              }
            }
 else {
              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))                   p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getPrice(event.getSlot())+ "String_Node_Str");
                }
              }
 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 {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getPrice()+ "String_Node_Str");
                }
              }
            }
          }
 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);
          }
        }
 else         if (trader.getStatus().equals(Status.PLAYER_BUY)) {
          si=sr.wantItemBuy(event.getSlot());
          if (si != null) {
            if (si.getItemStack().getType().equals(event.getCursor().getType())) {
              econ.depositPlayer(p.getName(),si.getPrice() * event.getCursor().getAmount());
              p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCursor().getAmount()+ "String_Node_Str"+ si.getPrice(event.getSlot())+ "String_Node_Str");
              event.setCursor(new ItemStack(Material.AIR));
            }
 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" + si.getPrice(event.getSlot())+ "String_Node_Str");
            }
          }
 else {
            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);
            }
          }
        }
        event.setCancelled(true);
      }
 else {
        StockItem si=null;
        if (top) {
          if (event.isShiftClick()) {
            if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              si=sr.itemForSell(event.getSlot());
              if (si != null) {
                trader.getInventory().clear();
                InventoryTrait.setInventoryWith(trader.getInventory(),si);
                trader.setStatus(Status.PLAYER_MANAGE_SELL_AMOUT);
                trader.setStockItem(si);
              }
 else {
                if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                  trader.setStatus(Status.PLAYER_MANAGE_PRICE);
                  trader.getInventory().clear();
                  sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_PRICE);
                }
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) {
              sr.saveNewAmouts(trader.getInventory(),trader.getStockItem());
              trader.getInventory().clear();
              sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
              trader.setStatus(Status.PLAYER_MANAGE_SELL);
              trader.setStockItem(null);
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
              if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)15)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                trader.setStatus(Status.PLAYER_MANAGE_SELL);
                trader.getInventory().clear();
                sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
              }
            }
            event.setCancelled(true);
          }
 else {
            if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              if (trader.getStockItem() == null) {
                trader.setStockItem(sr.itemForSell(event.getSlot()));
              }
 else {
                if (trader.getStockItem().getSlot() < 0) {
                  trader.getStockItem().getAmouts().clear();
                  trader.getStockItem().addAmout(event.getCursor().getAmount());
                  sr.addItem(true,trader.getStockItem());
                }
                StockItem item=trader.getStockItem();
                if (!event.getCurrentItem().getType().equals(Material.AIR))                 trader.setStockItem(sr.itemForSell(event.getSlot()));
 else                 trader.setStockItem(null);
                item.setSlot(event.getSlot());
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) {
              if (!event.getCursor().getType().equals(Material.AIR) && !(event.getCursor().getType().equals(trader.getStockItem().getItemStack().getType()) && event.getCursor().getData().equals(trader.getStockItem().getItemStack().getData())) || (!event.getCurrentItem().getType().equals(trader.getStockItem().getItemStack().getType()) && !event.getCurrentItem().getType().equals(Material.AIR))) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
              si=sr.itemForSell(event.getSlot());
              if (si == null)               si=sr.wantItemBuy(event.getSlot());
              if (si != null) {
                if (event.isLeftClick())                 si.increasePrice(this.getManagePriceAmout(event.getCursor()));
 else                 if (event.isRightClick())                 si.lowerPrice(this.getManagePriceAmout(event.getCursor()));
                p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getPrice() / si.getAmouts().get(0));
                event.setCancelled(true);
              }
 else               p.sendMessage(ChatColor.GOLD + "String_Node_Str");
            }
          }
          trader.setLastInv(true);
        }
 else {
          if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) || trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
            if (trader.getLastInv() && trader.getStockItem() != null) {
              sr.removeItem(true,trader.getStockItem().getSlot());
              trader.setStockItem(null);
            }
 else {
              ItemStack is=event.getCurrentItem();
              trader.setStockItem(new StockItem(is.getTypeId() + "String_Node_Str" + is.getAmount()));
            }
          }
 else {
          }
          trader.setLastInv(false);
        }
      }
    }
  }
}

Fixed version (ground truth):
@EventHandler public void inventoryClick(InventoryClickEvent event){
  if (event.getRawSlot() < 0)   return;
  if (event.getWhoClicked() instanceof Player) {
    Player p=(Player)event.getWhoClicked();
    if (state.containsKey(p.getName())) {
      TraderStatus trader=state.get(p.getName());
      InventoryTrait sr=trader.getTrader().getTrait(InventoryTrait.class);
      boolean top=event.getView().convertSlot(event.getRawSlot()) == event.getRawSlot();
      if ((!trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) && !trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) && !trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE) && top) {
        StockItem si=null;
        if (trader.getStatus().equals(Status.PLAYER_SELL) || trader.getStatus().equals(Status.PLAYER_SELL_AMOUT)) {
          if (trader.getStatus().equals(Status.PLAYER_SELL_AMOUT))           si=trader.getStockItem();
 else           si=sr.itemForSell(event.getSlot());
          if (si != null) {
            if (event.isShiftClick()) {
              if (si.hasMultipleAmouts() && trader.getStatus().equals(Status.PLAYER_SELL_AMOUT)) {
                if (econ.has(p.getName(),si.getPrice(event.getSlot()))) {
                  if (!event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)14)) && !event.getCurrentItem().getType().equals(Material.AIR)) {
                    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"+ si.getPrice(event.getSlot())+ "String_Node_Str");
                  }
                }
 else {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                }
              }
 else {
                if (econ.has(p.getName(),si.getPrice())) {
                  econ.withdrawPlayer(p.getName(),si.getPrice());
                  p.getInventory().addItem(si.getItemStack());
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getItemStack().getAmount()+ "String_Node_Str"+ si.getPrice()+ "String_Node_Str");
                }
 else {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                }
              }
            }
 else {
              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))                   p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getPrice(event.getSlot())+ "String_Node_Str");
                }
              }
 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 {
                  p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getPrice()+ "String_Node_Str");
                }
              }
            }
          }
 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);
          }
        }
 else         if (trader.getStatus().equals(Status.PLAYER_BUY)) {
          si=sr.wantItemBuy(event.getSlot());
          if (si != null) {
            if (si.getItemStack().getType().equals(event.getCursor().getType())) {
              econ.depositPlayer(p.getName(),si.getPrice() * event.getCursor().getAmount());
              p.sendMessage(ChatColor.GOLD + "String_Node_Str" + event.getCursor().getAmount()+ "String_Node_Str"+ si.getPrice(si.getSlot()) * event.getCursor().getAmount() + "String_Node_Str");
              event.setCursor(new ItemStack(Material.AIR));
            }
 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" + si.getPrice(event.getSlot())+ "String_Node_Str");
            }
          }
 else {
            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);
            }
          }
        }
        event.setCancelled(true);
      }
 else {
        StockItem si=null;
        if (top) {
          if (event.isShiftClick()) {
            if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              si=sr.itemForSell(event.getSlot());
              if (si != null) {
                trader.getInventory().clear();
                InventoryTrait.setInventoryWith(trader.getInventory(),si);
                trader.setStatus(Status.PLAYER_MANAGE_SELL_AMOUT);
                trader.setStockItem(si);
              }
 else {
                if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                  trader.setStatus(Status.PLAYER_MANAGE_PRICE);
                  trader.getInventory().clear();
                  sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_PRICE);
                }
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) {
              sr.saveNewAmouts(trader.getInventory(),trader.getStockItem());
              trader.getInventory().clear();
              sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
              trader.setStatus(Status.PLAYER_MANAGE_SELL);
              trader.setStockItem(null);
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
              if (event.getCurrentItem().equals(new ItemStack(Material.WOOL,1,(short)0,(byte)15)) && (event.getSlot() == trader.getInventory().getSize() - 2)) {
                trader.setStatus(Status.PLAYER_MANAGE_SELL);
                trader.getInventory().clear();
                sr.inventoryView(trader.getInventory(),Status.PLAYER_MANAGE_SELL);
              }
            }
            event.setCancelled(true);
          }
 else {
            if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL)) {
              if (trader.getStockItem() == null) {
                trader.setStockItem(sr.itemForSell(event.getSlot()));
              }
 else {
                if (trader.getStockItem().getSlot() < 0) {
                  trader.getStockItem().getAmouts().clear();
                  trader.getStockItem().addAmout(event.getCursor().getAmount());
                  sr.addItem(true,trader.getStockItem());
                }
                StockItem item=trader.getStockItem();
                if (!event.getCurrentItem().getType().equals(Material.AIR))                 trader.setStockItem(sr.itemForSell(event.getSlot()));
 else                 trader.setStockItem(null);
                item.setSlot(event.getSlot());
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL_AMOUT)) {
              if (!event.getCursor().getType().equals(Material.AIR) && !(event.getCursor().getType().equals(trader.getStockItem().getItemStack().getType()) && event.getCursor().getData().equals(trader.getStockItem().getItemStack().getData())) || (!event.getCurrentItem().getType().equals(trader.getStockItem().getItemStack().getType()) && !event.getCurrentItem().getType().equals(Material.AIR))) {
                p.sendMessage(ChatColor.GOLD + "String_Node_Str");
                event.setCancelled(true);
              }
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
            }
 else             if (trader.getStatus().equals(Status.PLAYER_MANAGE_PRICE)) {
              si=sr.itemForSell(event.getSlot());
              if (si == null)               si=sr.wantItemBuy(event.getSlot());
              if (si != null) {
                if (event.isLeftClick())                 si.increasePrice(this.getManagePriceAmout(event.getCursor()));
 else                 if (event.isRightClick())                 si.lowerPrice(this.getManagePriceAmout(event.getCursor()));
                p.sendMessage(ChatColor.GOLD + "String_Node_Str" + si.getPrice() / si.getAmouts().get(0));
                event.setCancelled(true);
              }
 else               p.sendMessage(ChatColor.GOLD + "String_Node_Str");
            }
          }
          trader.setLastInv(true);
        }
 else {
          if (trader.getStatus().equals(Status.PLAYER_MANAGE_SELL) || trader.getStatus().equals(Status.PLAYER_MANAGE_BUY)) {
            if (trader.getLastInv() && trader.getStockItem() != null) {
              sr.removeItem(true,trader.getStockItem().getSlot());
              trader.setStockItem(null);
            }
 else {
              ItemStack is=event.getCurrentItem();
              trader.setStockItem(new StockItem(is.getTypeId() + "String_Node_Str" + is.getAmount()));
            }
          }
 else {
          }
          trader.setLastInv(false);
        }
      }
    }
  }
}