Hello, my partner was playing Rimworld recently and ran into an odd issue. She was warned that hate chanters had showed up and would soon encroach on her settlement. After awhile she realized they were not actually coming. We used dev mode to clear fog and verified they were not actually hidden anywhere. When we checked the error log we noticed an issue with spawning pawns that I am guessing is related.

The errors we saw include the following:

Exception while ticking lord with job RimWorld.LordJob_HateChant:
System.InvalidOperationException: Sequence contains no elements
[Ref 504097D5]
at System.Linq.Enumerable.Average[TSource] (System.Collections.Generic.IEnumerable1[T] source, System.Func2[T,TResult] selector) [0x00030] in <1f993cbf88314b1baa1e10ca917bdc64>:0
at Verse.Gen.AveragePosition (System.Collections.Generic.List`1[T] cells) [0x00000] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.LordJob_HateChant.InitializeSfx () [0x0006c] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.LordJob_HateChant.TickSustainersAndMotes () [0x00010] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.LordJob_HateChant.LordJobTick () [0x00018] in <cb53cd4422904947932d33f561ad8d15>:0
at Verse.AI.Group.Lord.LordTick () [0x00072] in <cb53cd4422904947932d33f561ad8d15>:0
at Verse.AI.Group.LordManager.LordManagerTick () [0x00011] in <cb53cd4422904947932d33f561ad8d15>:0

Which I am guessing might be explained by this one:

Could not generate a pawn after 70 tries. Last error: Generated pawn incapable of violence. Ignoring scenario requirements.
Could not generate a pawn after 100 tries. Last error: Generated pawn incapable of violence. Ignoring validator.
Pawn generation error: Generated pawn incapable of violence. Too many tries (120), returning null. Generation request: kindDef=Tribal_Warrior, context=NonPlayer, faction=Batros League, tile=285309,0, forceGenerateNewPawn=False, allowedDevelopmentalStages=Adult, allowDead=False, allowDowned=False, canGeneratePawnRelations=True, mustBeCapableOfViolence=True, colonistRelationChanceFactor=1, forceAddFreeWarmLayerIfNeeded=False, allowGay=True, prohibitedTraits=, allowFood=True, allowAddictions=True, inhabitant=False, certainlyBeenInCryptosleep=False, biocodeWeaponChance=0, validatorPreGear=, validatorPostGear=, fixedBiologicalAge=, fixedChronologicalAge=, fixedGender=, fixedLastName=, fixedBirthName=
Error while generating pawn. Rethrowing. Exception: System.NullReferenceException: Object reference not set to an instance of an object
[Ref 9E8FC06F]
at Verse.PawnGenerator.GeneratePawn (Verse.PawnGenerationRequest request) [0x00114] in <cb53cd4422904947932d33f561ad8d15>:0
Exception while generating pawn group: System.NullReferenceException: Object reference not set to an instance of an object
[Ref C661F878]
at Verse.PawnGenerator.GeneratePawn (Verse.PawnGenerationRequest request) [0x00188] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.PawnGroupKindWorker_Normal.GeneratePawns (RimWorld.PawnGroupMakerParms parms, RimWorld.PawnGroupMaker groupMaker, System.Collections.Generic.List`1[T] outPawns, System.Boolean errorOnZeroResults) [0x002d1] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.PawnGroupKindWorker.GeneratePawns (RimWorld.PawnGroupMakerParms parms, RimWorld.PawnGroupMaker groupMaker, System.Boolean errorOnZeroResults) [0x00011] in <cb53cd4422904947932d33f561ad8d15>:0

Finally, shortly after this her mech link quest also failed. I cannot see how this might be related but I also cannot explain this away in the context of her other mods. Just in case, I wanted to include it.

Exception running QuestNode_Root_MechanitorShip: System.IndexOutOfRangeException: Index was outside the bounds of the array.
[Ref 13B62BCC]
at Verse.TerrainGrid.FoundationAt (Verse.IntVec3 c) [0x00017] in <cb53cd4422904947932d33f561ad8d15>:0
at Verse.GridsUtility.GetAffordances (Verse.IntVec3 c, Verse.Map map) [0x00000] in <cb53cd4422904947932d33f561ad8d15>:0
at Verse.GenGrid.SupportsStructureType (Verse.IntVec3 c, Verse.Map map, Verse.TerrainAffordanceDef surfaceType) [0x00000] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.DropCellFinder.IsSafeDropSpot (Verse.IntVec3 cell, Verse.Map map, RimWorld.Faction faction, System.Nullable`1[T] size, System.Int32 distToEdge, System.Int32 distToHostiles, System.Int32 distToFires, System.Nullable`1[T] interactionCell) [0x0005d] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.DropCellFinder.FindSafeLandingSpot (Verse.IntVec3& spot, RimWorld.Faction faction, Verse.Map map, System.Int32 distToHostiles, System.Int32 distToFires, System.Int32 distToEdge, System.Nullable`1[T] size, System.Nullable`1[T] interactionCell) [0x0001b] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.QuestGen.QuestNode_Root_MechanitorShip.TryFindShuttleCrashPosition (Verse.Map map, Verse.IntVec2 size, Verse.IntVec3& spot) [0x00022] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.QuestGen.QuestNode_Root_MechanitorShip.RunInt () [0x00306] in <cb53cd4422904947932d33f561ad8d15>:0
at RimWorld.QuestGen.QuestNode.Run () [0x00015] in <cb53cd4422904947932d33f561ad8d15>:0

Her mods:
brrainz.harmony
Ludeon.RimWorld
Ludeon.RimWorld.Royalty
Ludeon.RimWorld.Ideology
Ludeon.RimWorld.Biotech
Ludeon.RimWorld.Anomaly
Ludeon.RimWorld.Odyssey
DarthSergeant.NurseJob
rimfridge.kv.rw
PeteTimesSix.SimpleSidearms
EdB.PrepareCarefully
bs.xenotypespawncontrol
Sandy.RPGStyleInventory.avilmask.Revamped
IwoRosiak.Holsters
esvn.RPGDialog