===Error log===
System.NullReferenceException: Object reference not set to an instance of an object
at NR_AutoMachineTool.Building_Repairer+<>c.<TryStartWorking>b__14_7 (Verse.Pawn p) [0x00015] in <74570a4a7a2e49b3b78d778391fd1443>:0
at System.Linq.Utilities+<>c__DisplayClass1_0`1[TSource].<CombinePredicates>b__0 (TSource x) [0x0000e] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
at System.Linq.Enumerable+WhereListIterator`1[TSource].MoveNext () [0x00037] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
at NR_AutoMachineTool.Utilities.Ops.FirstOption[T] (System.Collections.Generic.IEnumerable`1[T] e) [0x00007] in <74570a4a7a2e49b3b78d778391fd1443>:0
at NR_AutoMachineTool.Building_Repairer.TryStartWorking (NR_AutoMachineTool.Building_Repairer& target, System.Single& workAmount) [0x00196] in <74570a4a7a2e49b3b78d778391fd1443>:0
at NR_AutoMachineTool.Building_Base`1[T].Ready () [0x0003a] in <74570a4a7a2e49b3b78d778391fd1443>:0
at NR_AutoMachineTool.Building_BaseRange`1[T].Ready () [0x00000] in <74570a4a7a2e49b3b78d778391fd1443>:0
at NR_AutoMachineTool.MapTickManager.Exec (System.Action act) [0x00000] in <74570a4a7a2e49b3b78d778391fd1443>:0
Verse.Log:Error(String, Boolean)
NR_AutoMachineTool.MapTickManager:Exec(Action)
System.Collections.Generic.List`1:ForEach(Action`1)
NR_AutoMachineTool.<>c:<MapComponentTick>b__1_1(HashSet`1)
NR_AutoMachineTool.Utilities.Option`1:ForEach(Action`1)
NR_AutoMachineTool.MapTickManager:MapComponentTick()
Verse.MapComponentUtility:MapComponentTick(Map)
Verse.Map:MapPostTick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:DMD<DMD<Update_Patch1>?1688577024::Update_Patch1>(Root_Play)


Not sure what causes it, it pops up randomly in my game.