What is the reason for this error? and how to fix it?

I'll see if i an reproduce the error. Im sure there is something that its trying to do and cannot process the code.

I'm getting the same message now.

Failed to call hook 'OnEntityTakeDamage' on plugin 'VIPNoDecay v1.0.1' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.VIPNoDecay.OnEntityTakeDamage (BaseCombatEntity entity, HitInfo hitInfo) [0x00047] in <e2728b0b583148998c876426870a1ede>:0
at Oxide.Plugins.VIPNoDecay.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00087] in <e2728b0b583148998c876426870a1ede>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <98321e516fc1420ea57d4d2088213a59>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <ac41dd3599754d448b8c218b34645820>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <ac41dd3599754d448b8c218b34645820>:0

does it happen constantly? or just once here and there? ill see if i can duplicate it and fix :)