Here's the full log of the error. Not sure what's causing it. Sometimes it happens & it stops as soon as I disconnect when there's no one else on the server. But this morning I spotted it happening when the server was empty.

NullReferenceException: Object reference not set to an instance of an object
  at NPCPlayerApex.OnAiQuestion (NPCPlayerApex source, Rust.Ai.AiQuestion_ShareEnemyTarget question) [0x000a7] in <c44bcbbacce34ba9802838be07d2459c>:0 
  at Scientist.AskQuestion (Rust.Ai.AiQuestion_ShareEnemyTarget question, System.Collections.Generic.List`1[Rust.Ai.AiAnswer_ShareEnemyTarget]& answers) [0x0002c] in <c44bcbbacce34ba9802838be07d2459c>:0 
  at Rust.Ai.SharePlayerTargetComm.Execute (Rust.Ai.PlayerTargetContext c) [0x00018] in <c44bcbbacce34ba9802838be07d2459c>:0 
  at Apex.AI.ActionBase`1[TContext].Apex.AI.IAction.Execute (Apex.AI.IAIContext context) [0x00000] in <941505ea7bfb40aa8f39d056a6448dba>:0 
  at Apex.AI.CompositeAction.Execute (Apex.AI.IAIContext context) [0x0001c] in <941505ea7bfb40aa8f39d056a6448dba>:0 
  at Apex.AI.Components.UtilityAIClient.Execute () [0x00055] in <941505ea7bfb40aa8f39d056a6448dba>:0 
  at NPCPlayerApex.TickSensorySystem () [0x000c7] in <c44bcbbacce34ba9802838be07d2459c>:0 
  at NPCPlayerApex.Apex.LoadBalancing.ILoadBalanced.ExecuteUpdate (System.Single deltaTime, System.Single nextInterval) [0x00038] in <c44bcbbacce34ba9802838be07d2459c>:0 
  at Apex.LoadBalancing.LoadBalancedQueue.Update () [0x00095] in <b8069b123e61411c93391e966a5a1439>:0 
  at Apex.LoadBalancing.LoadBalancerComponent.Update () [0x00004] in <b8069b123e61411c93391e966a5a1439>:0

https://oxidemod.org/threads/nullreferenceexception-at-npcplayerapex-onaiquestion.31406/ - Solution

That doesn't help. Just about people with the same problem & give's no fixes. From what I could tell, its something to do with BotSpawn & Bandit camp!

How to apply the proposed solution?
var botapex = entity.GetComponent(); botapex.CommunicationRadius = 0f;