I'm not 100% certain this is related to this mod, but the name was a close match:

Null key while loading dictionary of Verse.Pawn and ColonistHistory.ColonistHistoryDataList. label=colonistHistories
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) Verse.Log:Verse.Log.Error_Patch6 (string)
Verse.Scribe_Collections:Look<Verse.Pawn, ColonistHistory.ColonistHistoryDataList> (System.Collections.Generic.Dictionary`2<Verse.Pawn, ColonistHistory.ColonistHistoryDataList>&,string,Verse.LookMode,Verse.LookMode,System.Collections.Generic.List`1<Verse.Pawn>&,System.Collections.Generic.List`1<ColonistHistory.ColonistHistoryDataList>&,bool)
ColonistHistory.GameComponent_ColonistHistoryRecorder:ExposeData ()
Verse.CrossRefHandler:ResolveAllCrossReferences ()
Verse.ScribeLoader:FinalizeLoading ()
(wrapper dynamic-method) Verse.Game:Verse.Game.LoadGame_Patch9 (Verse.Game)
(wrapper dynamic-method) Verse.SavedGameLoaderNow:Verse.SavedGameLoaderNow.LoadGameFromSaveFileNow_Patch4 (string)
Verse.Root_Play/<>c:<Start>b__1_1 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__27_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()