error in web panel

 Failed to call hook 'welcomepanel_open' on plugin 'WelcomePanel v3.0.7' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.WelcomePanel.OpenAddOn_API (BasePlayer player, System.String _apiName) [0x000c0] in <5fcfc9c6200f4a418a405c2669243dc8>:0 
  at Oxide.Plugins.WelcomePanel.CreateTab (BasePlayer player, System.Int32 tabNumber, System.Int32 pageNumber) [0x012d8] in <5fcfc9c6200f4a418a405c2669243dc8>:0 
  at Oxide.Plugins.WelcomePanel.welcomepanel_open (ConsoleSystem+Arg arg) [0x0004c] in <5fcfc9c6200f4a418a405c2669243dc8>:0 
  at Oxide.Plugins.WelcomePanel.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00d29] in <5fcfc9c6200f4a418a405c2669243dc8>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <60c318df79ed41688ea59335e48d61ad>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <dfcb48ea05694263bbc08e62a39c274c>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <dfcb48ea05694263bbc08e62a39c274c>:0

Changed Status from Pending to Not a Bug

That is related to config, you probably deleted something or just missed some value.