System.NullReferenceException: Object reference not set to an instance of an object
  at MoreFactionInteraction.World_Incidents.SitePartWorker_MigratoryHerd+<>c__DisplayClass3_0.<TryFindAnimalKind>b__0 (Verse.PawnKindDef k) [0x00000] in <filename unknown>:0 
  at System.Linq.Enumerable+<CreateWhereIterator>c__Iterator1D`1[Verse.PawnKindDef].MoveNext () [0x00000] in <filename unknown>:0 
  at Verse.GenCollection.TryRandomElementByWeight[PawnKindDef] (IEnumerable`1 source, System.Func`2 weightSelector, Verse.PawnKindDef& result) [0x00000] in <filename unknown>:0 
  at Verse.GenCollection.RandomElementByWeightWithFallback[PawnKindDef] (IEnumerable`1 source, System.Func`2 weightSelector, Verse.PawnKindDef fallback) [0x00000] in <filename unknown>:0 
  at MoreFactionInteraction.World_Incidents.SitePartWorker_MigratoryHerd.TryFindAnimalKind (Int32 tile, Verse.PawnKindDef& animalKind) [0x00000] in <filename unknown>:0 
  at MoreFactionInteraction.World_Incidents.SitePartWorker_MigratoryHerd.GenerateDefaultParams (RimWorld.Planet.Site site, Single myThreatPoints) [0x00000] in <filename unknown>:0 
  at RimWorld.Planet.SiteMaker.MakeSite (RimWorld.SiteCoreDef core, IEnumerable`1 siteParts, Int32 tile, RimWorld.Faction faction, Boolean ifHostileThenMustRemainHostile, Nullable`1 threatPoints) [0x00000] in <filename unknown>:0 
  at RimWorld.Planet.SiteMaker.MakeSite (RimWorld.SiteCoreDef core, RimWorld.SitePartDef sitePart, Int32 tile, RimWorld.Faction faction, Boolean ifHostileThenMustRemainHostile, Nullable`1 threatPoints) [0x00000] in <filename unknown>:0 
  at MoreFactionInteraction.World_Incidents.IncidentWorker_HuntersLodge.TryExecuteWorker (RimWorld.IncidentParms parms) [0x00000] in <filename unknown>:0 
  at RimWorld.IncidentWorker.TryExecute (RimWorld.IncidentParms parms) [0x00000] in <filename unknown>:0 
  at RimWorld.Storyteller.TryFire (RimWorld.FiringIncident fi) [0x00000] in <filename unknown>:0 
  at RimWorld.IncidentQueue.IncidentQueueTick () [0x00000] in <filename unknown>:0 
  at RimWorld.Storyteller.StorytellerTick () [0x00000] in <filename unknown>:0 
  at Verse.TickManager.DoSingleTick () [0x00000] in <filename unknown>:0 
Verse.Log:Error(String, Boolean)
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate_Patch0(Object)
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()