Misc. MAI Joberror

JobDriver threw exception in initAction. Pawn=Leo, Job=DoBill A=Thing_AIPawn326886, Exception: System.NullReferenceException: Object reference not set to an instance of an object
  at RimWorld.Bill_Medical.Notify_DoBillStarted (Verse.Pawn billDoer) [0x00000] in <filename unknown>:0
  at Verse.AI.Toils_Recipe+<DoRecipeWork>c__AnonStorey4A6.<>m__77B () [0x00000] in <filename unknown>:0
  at Verse.AI.JobDriver.TryActuallyStartNextToil () [0x00000] in <filename unknown>:0  lastJobGiver=RimWorld.JobGiver_Work, curJob.def=DoBill, curDriver=Verse.AI.JobDriver_DoBill
Verse.Log:Error(String)
Verse.AI.Pawn_JobTracker:StartErrorRecoverJob(String)
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.JobDriver:Notify_PatherArrived()
Verse.AI.Pawn_PathFollower:PatherArrived()
Verse.AI.Pawn_PathFollower:StartPath(LocalTargetInfo, PathEndMode)
Verse.AI.<GotoThing>c__AnonStorey4F2:<>m__7DA()
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.JobDriver:JumpToToil(Toil)
Verse.AI.<JumpIf>c__AnonStorey4EC:<>m__7D4()
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:ReadyForNextToil()
Verse.AI.Pawn_JobTracker:StartJob(Job, JobCondition, ThinkNode, Boolean, Boolean, ThinkTreeDef, Nullable`1)
Verse.AI.Pawn_JobTracker:TryFindAndStartJob()
Verse.AI.Pawn_JobTracker:EndCurrentJob(JobCondition, Boolean)
Verse.AI.Pawn_JobTracker:JobTrackerTick()
Verse.Pawn:Tick()
Verse.TickList:Tick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()