System.NullReferenceException: Object reference not set to an instance of an object
  at DynamicDiplomacy.IncidentWorker_NPCConquest+<>c.<RandomSettlement>b__7_0 (RimWorld.Planet.Settlement settlement) [0x00006] in <e04e9cda3f8d468a9430a8f44146946d>:0
  at System.Linq.Enumerable+WhereListIterator`1[TSource].ToList () [0x00017] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
  at System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x0001f] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
  at Verse.GenCollection.TryRandomElement[T] (System.Collections.Generic.IEnumerable`1[T] source, T& result) [0x00029] in <7927e938de4c4089b4add4215e58d5b1>:0
  at Verse.GenCollection.RandomElementWithFallback[T] (System.Collections.Generic.IEnumerable`1[T] source, T fallback) [0x00000] in <7927e938de4c4089b4add4215e58d5b1>:0
  at DynamicDiplomacy.IncidentWorker_NPCConquest.RandomSettlement () [0x0002f] in <e04e9cda3f8d468a9430a8f44146946d>:0
  at DynamicDiplomacy.IncidentWorker_NPCConquest.CanFireNowSub (RimWorld.IncidentParms parms) [0x0000a] in <e04e9cda3f8d468a9430a8f44146946d>:0
  at RimWorld.IncidentWorker.CanFireNow (RimWorld.IncidentParms parms, System.Boolean forced) [0x00178] in <7927e938de4c4089b4add4215e58d5b1>:0
  at RimWorld.StorytellerComp+<>c__DisplayClass6_0.<UsableIncidentsInCategory>b__0 (RimWorld.IncidentDef x) [0x00020] in <7927e938de4c4089b4add4215e58d5b1>:0
  at System.Linq.Utilities+<>c__DisplayClass1_0`1[TSource].<CombinePredicates>b__0 (TSource x) [0x00000] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
  at System.Linq.Enumerable+WhereListIterator`1[TSource].MoveNext () [0x00037] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
  at Verse.GenCollection.TryRandomElementByWeight[T] (System.Collections.Generic.IEnumerable`1[T] source, System.Func`2[T,TResult] weightSelector, T& result) [0x0021e] in <7927e938de4c4089b4add4215e58d5b1>:0
  at RimWorld.StorytellerComp_CategoryMTB+<MakeIntervalIncidents>d__2.MoveNext () [0x0008e] in <7927e938de4c4089b4add4215e58d5b1>:0
  at RimWorld.Storyteller+<MakeIncidentsForInterval>d__21.MoveNext () [0x00171] in <7927e938de4c4089b4add4215e58d5b1>:0
  at RimWorld.Storyteller+<MakeIncidentsForInterval>d__20.MoveNext () [0x000a1] in <7927e938de4c4089b4add4215e58d5b1>:0
  at (wrapper dynamic-method) RimWorld.Storyteller.RimWorld.Storyteller.StorytellerTick_Patch1(RimWorld.Storyteller)
  at (wrapper dynamic-method) Verse.TickManager.Verse.TickManager.DoSingleTick_Patch5(Verse.TickManager)
Verse.Log:Verse.Log.Error_Patch2(String, Boolean)
Verse.TickManager:Verse.TickManager.DoSingleTick_Patch5(TickManager)
Verse.TickManager:Verse.TickManager.TickManagerUpdate_Patch1(TickManager)
Verse.Game:Verse.Game.UpdatePlay_Patch2(Game)
Verse.Root_Play:Verse.Root_Play.Update_Patch1(Root_Play)