On finishing the building of the helicopter the building disappears. This error occurs:

Exception in JobDriver tick for pawn Willie driver=JobDriver_ConstructFinishFrame (toilIndex=1) driver.job=(FinishFrame (Job_10007315) A=Thing_Frame_Building_Helicopter1931855) lastJobGiver=RimWorld.JobGiver_Work
System.ArgumentNullException: Argument cannot be null.
Parameter name: type
at System.Activator.CheckType (System.Type) <0x00095>
at System.Activator.CreateInstance (System.Type,bool) <0x00027>
at System.Activator.CreateInstance (System.Type) <0x0001e>
at Verse.ThingMaker.MakeThing (Verse.ThingDef,Verse.ThingDef) <0x0035e>
at RimWorld.Frame.CompleteConstruction (Verse.Pawn) <0x00309>
at RimWorld.JobDriver_ConstructFinishFrame/<MakeNewToils>c__Iterator0/<MakeNewToils>c__AnonStorey1.<>m__1 () <0x00396>
at (wrapper dynamic-method) Verse.AI.JobDriver.DriverTick_Patch1 (object) <0x004c8>

Verse.Log:Error(String, Boolean)
Verse.AI.JobUtility:TryStartErrorRecoverJob(Pawn, String, Exception, JobDriver)
Verse.AI.JobDriver:DriverTick_Patch1(Object)
Verse.AI.Pawn_JobTracker:JobTrackerTick()
Verse.Pawn:Tick_Patch1(Object)
Verse.TickList:Tick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()