Null reference error

Exception from long event: System.NullReferenceException: Object reference not set to an instance of an object
at AnimalTab.MainTabWindow_Animals.RecachePawns () [0x00006] in <a3f8e18f660f41d69043a3c2f56d9bf4>:0
at AnimalTab.MainTabWindow_Animals.get_AllPawns () [0x00008] in <a3f8e18f660f41d69043a3c2f56d9bf4>:0
at AnimalTab.MainTabWindow_Animals.get_Pawns () [0x00008] in <a3f8e18f660f41d69043a3c2f56d9bf4>:0
at RimWorld.MainTabWindow_PawnTable.<CreateTable>b__17_0 () [0x00000] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.PawnTable.RecachePawns () [0x0000b] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.PawnTable.RecacheIfDirty () [0x00010] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.PawnTable.get_Size () [0x00000] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.MainTabWindow_PawnTable.get_RequestedTabSize () [0x0000e] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.MainTabWindow.get_InitialSize () [0x00000] in <1dc590b40aa1431cbb94285149d6a29f>:0
at Verse.Window.SetInitialSizeAndPosition () [0x00000] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.MainTabWindow.SetInitialSizeAndPosition () [0x00000] in <1dc590b40aa1431cbb94285149d6a29f>:0
at AnimalTab.MainTabWindow_Animals.SetInitialSizeAndPosition () [0x00000] in <a3f8e18f660f41d69043a3c2f56d9bf4>:0
at RimWorld.MainTabWindow_PawnTable.SetDirty () [0x0000b] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.MainTabWindow_PawnTable.PostOpen () [0x0001a] in <1dc590b40aa1431cbb94285149d6a29f>:0
at Verse.WindowStack.Add (Verse.Window window) [0x0003a] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.MainTabsRoot.ToggleTab (RimWorld.MainButtonDef newTab, System.Boolean playSound) [0x0006b] in <1dc590b40aa1431cbb94285149d6a29f>:0
at RimWorld.MainTabsRoot.SetCurrentTab (RimWorld.MainButtonDef tab, System.Boolean playSound) [0x0000a] in <1dc590b40aa1431cbb94285149d6a29f>:0
at (wrapper dynamic-method) RimWorld.MapInterface.RimWorld.MapInterface.Notify_SwitchedMap_Patch1(RimWorld.MapInterface)
at Verse.Game.set_CurrentMap (Verse.Map value) [0x00039] in <1dc590b40aa1431cbb94285149d6a29f>:0
at (wrapper dynamic-method) Verse.Game.Verse.Game.DeinitAndRemoveMap_Patch1(Verse.Game,Verse.Map)
at MapReroll.RerollToolbox.DiscardFactionBase (RimWorld.Planet.MapParent mapParent) [0x0000b] in <9d47e862ce99494ea06519b173a182e3>:0
at MapReroll.RerollToolbox+<>c__DisplayClass2_0.<DoMapReroll>b__0 () [0x000a1] in <9d47e862ce99494ea06519b173a182e3>:0
at Verse.LongEventHandler.UpdateCurrentSynchronousEvent (System.Boolean& sceneChanged) [0x0001d] in <1dc590b40aa1431cbb94285149d6a29f>:0
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.LongEventHandler:UpdateCurrentSynchronousEvent (bool&)
Verse.LongEventHandler:LongEventsUpdate (bool&)
(wrapper dynamic-method) Verse.Root:Verse.Root.Update_Patch1 (Verse.Root)
Verse.Root_Play:Update ()