NullReferenceException at IOnServerCommandError
Failed to call hook 'IOnServerCommand' on plugin 'ReignOfKingsCore v2.0.3854' (NullReferenceException: Object reference not set to an instance of an object)
  at CodeHatch.Common.PlayerExtensions.SendMessage (CodeHatch.Engine.Networking.Player player, System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsPlayer.Message (System.String message, System.String prefix, System.Object[] args) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsPlayer.Message (System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Core.Plugins.Plugin.CovalenceCommandCallback (IPlayer caller, System.String cmd, System.String[] args) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsCommandSystem.ChatCommandCallback (IPlayer caller, System.String cmd, System.String[] args) [0x00000] in <filename unknown>:0
  at Oxide.Core.Libraries.Covalence.CommandHandler.HandleCommand (IPlayer player, System.String command, System.String[] args) [0x00000] in <filename unknown>:0
  at Oxide.Core.Libraries.Covalence.CommandHandler.HandleChatMessage (IPlayer player, System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsCommandSystem.HandleChatMessage (IPlayer player, System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.ReignOfKingsCore.IOnServerCommand (UInt64 id, System.String str) [0x00000] in <filename unknown>:0
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0

You can't run the commands as a Server with a new Oxide build. I think it is because the server player is ignored. That blocks RCON usage and all Oxide commands as a server.

Pushed a change that'll hopefully resolve this for you. You can test with a development build.

19:59 [Error] Failed to call hook 'IOnServerCommand' on plugin 'ReignOfKingsCore v2.0.3860' (NullReferenceException: Object reference not set to an instance of an object)
  at CodeHatch.Common.PlayerExtensions.SendMessage (CodeHatch.Engine.Networking.Player player, System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsPlayer.Message (System.String message, System.String prefix, System.Object[] args) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsPlayer.Message (System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Core.Plugins.Plugin.CovalenceCommandCallback (IPlayer caller, System.String cmd, System.String[] args) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsCommandSystem.ChatCommandCallback (IPlayer caller, System.String cmd, System.String[] args) [0x00000] in <filename unknown>:0
  at Oxide.Core.Libraries.Covalence.CommandHandler.HandleCommand (IPlayer player, System.String command, System.String[] args) [0x00000] in <filename unknown>:0
  at Oxide.Core.Libraries.Covalence.CommandHandler.HandleChatMessage (IPlayer player, System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.Libraries.Covalence.ReignOfKingsCommandSystem.HandleChatMessage (IPlayer player, System.String message) [0x00000] in <filename unknown>:0
  at Oxide.Game.ReignOfKings.ReignOfKingsCore.IOnServerCommand (UInt64 playerId, System.String str) [0x00000] in <filename unknown>:0
  at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00000] in <filename unknown>:0
19:59 [Info] [CommandLog] Server (9999999999) ran command: giveto SteamID Stone Block 1

Which plugin are you using for the giveto command?