I am getting the following error in Console. I use NexusCheatRadar, ServerArmour, and Arkan together... 

03/10 6:37:52 PM | Failed to call hook 'API_GetIsProfilePrivate' on plugin 'ServerArmour v2.83.7' (NullReferenceException: Object reference not set to an instance of an object) at Oxide.Plugins.ServerArmour.IsProfilePrivate (System.String steamid) [0x00007] in <0483bf6a60ba4f01a59f8853a5ef2bf0>:0 at Oxide.Plugins.ServerArmour.API_GetIsProfilePrivate (System.String steamid) [0x00000] in <0483bf6a60ba4f01a59f8853a5ef2bf0>:0 at Oxide.Plugins.ServerArmour.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x014a9] in <0483bf6a60ba4f01a59f8853a5ef2bf0>:0 at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0 at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <15f61ddda771464d8246ebdce8ff4811>:0 at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <15f61ddda771464d8246ebdce8ff4811>:0 03/10 6:37:52 PM | Failed to call hook 'API_GetProfileLevel' on plugin 'ServerArmour v2.83.7' (NullReferenceException: Object reference not set to an instance of an object) at Oxide.Plugins.ServerArmour.GetProfileLevel (System.String steamid) [0x00007] in <0483bf6a60ba4f01a59f8853a5ef2bf0>:0 at Oxide.Plugins.ServerArmour.API_GetProfileLevel (System.String steamid) [0x00000] in <0483bf6a60ba4f01a59f8853a5ef2bf0>:0 at Oxide.Plugins.ServerArmour.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x015a6] in <0483bf6a60ba4f01a59f8853a5ef2bf0>:0 at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0 at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <15f61ddda771464d8246ebdce8ff4811>:0 at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <15f61ddda771464d8246ebdce8ff4811>:0

Based on what the console is spewing out, these methods need a null/cache guard?
NexusCheatRadar queried ServerArmour before ServerArmour had finished populating that player’s cache entry, or the cache entry was missing/failed for that player.

private bool API_GetIsProfilePrivate(string steamid) => IsProfilePrivate(steamid);
private int API_GetProfileLevel(string steamid) => GetProfileLevel(steamid);

Because ... if player == null, both throw.
bool IsProfilePrivate(string steamid)
{
ISAPlayer player = GetPlayerCache(steamid);
return player.communityvisibilitystate == 1;
}

int GetProfileLevel(string steamid)
{
ISAPlayer player = GetPlayerCache(steamid);
return (int)player.steamlevel;
}

You could look at changing it to;
private bool API_GetIsProfilePrivate(string steamid) =>
IsPlayerCached(steamid) && GetPlayerCache(steamid) != null
? GetPlayerCache(steamid).communityvisibilitystate == 1
: false;

private int API_GetProfileLevel(string steamid) =>
IsPlayerCached(steamid) && GetPlayerCache(steamid) != null
? (int)GetPlayerCache(steamid).steamlevel
: 0;

or fix the underlying helper methods?