[Error] Failed to call hook 'OnItemAction' on plugin 'SkullCrusher v1.1.0' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.SkullCrusher.IsTeamed (BasePlayer ownerPlayer, BasePlayer skullOwner) [0x00136] in <c7f73a7a6f2f4aa18c8fd7c775af362a>:0

  at Oxide.Plugins.SkullCrusher.OnItemAction (Item item, System.String action) [0x00132] in <c7f73a7a6f2f4aa18c8fd7c775af362a>:0

  at Oxide.Plugins.SkullCrusher.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00292] in <c7f73a7a6f2f4aa18c8fd7c775af362a>:0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <3606d2af539c45e4b5c61658e6a8b307>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <c2afd8354b8b4f3ca451cf5a1aa111c3>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <c2afd8354b8b4f3ca451cf5a1aa111c3>:0

appreciate any help thanks