I have the latest version and config.  Any ideas on how to fix?

 [Error] Failed to call hook 'TreeCommand' on plugin 'TreePlanter v1.2.2' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.TreePlanter.ListTrees (BasePlayer player) [0x0006f] in <5b7e2b0baeec48a28eca3464127fc9e8>:0

  at Oxide.Plugins.TreePlanter.TreeCommand (Oxide.Core.Libraries.Covalence.IPlayer player, System.String command, System.String[] args) [0x0000f] in <5b7e2b0baeec48a28eca3464127fc9e8>:0

  at Oxide.Plugins.TreePlanter.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00244] in <5b7e2b0baeec48a28eca3464127fc9e8>: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 <d5f57e12edfe4fa0b5c5dbdd9b51eff8>:0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <d5f57e12edfe4fa0b5c5dbdd9b51eff8>:0