NRE console spam, plugin not working (for me)

Failed to call hook 'OnNpcTarget' on plugin 'BetterAdmin v1.0.0' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Core.Libraries.Permission.UserHasPermission (System.String playerId, System.String permission) [0x0000a] in <beb2b64691c64e2b95b99491bd85442c>:0 
  at Oxide.Plugins.BetterAdmin.UserHasPermission (BasePlayer player, System.String permissionName) [0x00017] in <48decbda07d5459bb00ff2cf15d9c7b2>:0 
  at Oxide.Plugins.BetterAdmin.IsBetter (BasePlayer player) [0x00013] in <48decbda07d5459bb00ff2cf15d9c7b2>:0 
  at Oxide.Plugins.BetterAdmin.CheckTarget (BasePlayer player) [0x00009] in <48decbda07d5459bb00ff2cf15d9c7b2>:0 
  at Oxide.Plugins.BetterAdmin.OnNpcTarget (BaseEntity npc, BasePlayer entity) [0x00000] in <48decbda07d5459bb00ff2cf15d9c7b2>:0 
  at Oxide.Plugins.BetterAdmin.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0036e] in <48decbda07d5459bb00ff2cf15d9c7b2>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <795304323ac74a298b8ed190a1dfa739>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <beb2b64691c64e2b95b99491bd85442c>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <beb2b64691c64e2b95b99491bd85442c>:0 

Hi,
this error keeps spamming repeatedly and the plugin is not functional. 
Any help is appreciated.