Plugin Throwing Random Errors?

Hey guys. So today I have an odd problem that needs fixing. So I have multiple Items that open inventories, and they work!. Usually whenever I use it, it throws an error. Notice I said usually. Here's the log: http://pastebin.com/A1ZbTTrg
And here's the opening code:

Code:

@EventHandler
  public void interactEvent(PlayerInteractEvent event){
      Player p = event.getPlayer();
    
      if(p.getItemInHand() !=null){
          ItemStack item = p.getItemInHand();
        
          if(item.getType() == Material.CHEST){
              p.openInventory(cosmeticsInventory);
          }else{
              return;
          }
      }else{
          return;
      }
  }

Thanks!

 

@MCJoshua345, disguisecraft for your Bukkit version is broken,
also,

1. Caused by: java.lang.NullPointerException
2. at com.infinity.lobby.listeners.EventHandlers.pInteractEvent(EventHandlers.java:65) ~[?:?]

http://bukkit.org/threads/how-to-re...ubleshoot-your-own-plugins-by-yourself.32457/