Failed to call hook 'OnLeaveNPC' on plugin 'GUIShop v2.2.48' (NullReferenceException: )
  at (wrapper managed-to-native) UnityEngine.Component.get_transform(UnityEngine.Component)
  at BaseEntity.get_ServerPosition () [0x00000] in :0

  at Oxide.Plugins.GUIShop.OnLeaveNPC (BasePlayer npc, BasePlayer player) [0x00018] in :0

  at Oxide.Plugins.GUIShop.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x01aa8] in :0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <09575a60985045248bcb43b20faeeb99>:0

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

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

That is a guishop error not humanNPC