Every time one of my pawns finishes a bill, nothing is created and the resources are wasted.
This error pops up as well;

JobDriver threw exception in initAction for pawn Matthew driver=JobDriver_DoBill (toilIndex=13) driver.job=(DoBill (Job_2482278) A=Thing_FabricationBench552826 B=Thing_UnfinishedGun671517 C=(209, 0, 115))
System.ArgumentNullException: Value cannot be null.
Parameter name: type
at System.Activator.CreateInstance (System.Type type, System.Boolean nonPublic) [0x00003] in <567df3e0919241ba98db88bec4c6696f>:0
at System.Activator.CreateInstance (System.Type type) [0x00000] in <567df3e0919241ba98db88bec4c6696f>:0
at Verse.ThingMaker.MakeThing (Verse.ThingDef def, Verse.ThingDef stuff) [0x000ac] in <7927e938de4c4089b4add4215e58d5b1>:0
at Verse.GenRecipe+<MakeRecipeProducts>d__0.MoveNext () [0x000ef] in <7927e938de4c4089b4add4215e58d5b1>:0
at System.Collections.Generic.List`1[T]..ctor (System.Collections.Generic.IEnumerable`1[T] collection) [0x00077] in <567df3e0919241ba98db88bec4c6696f>:0
at System.Linq.Enumerable.ToList[TSource] (System.Collections.Generic.IEnumerable`1[T] source) [0x00018] in <351e49e2a5bf4fd6beabb458ce2255f3>:0
at Verse.AI.Toils_Recipe+<>c__DisplayClass3_0.<FinishRecipeAndStartStoringProduct>b__0 () [0x000a2] in <7927e938de4c4089b4add4215e58d5b1>:0
at Verse.AI.JobDriver.TryActuallyStartNextToil () [0x001df] in <7927e938de4c4089b4add4215e58d5b1>:0
Verse.Log:Verse.Log.Error_Patch2(String, Boolean)
Verse.AI.JobUtility:TryStartErrorRecoverJob(Pawn, String, Exception, JobDriver)
Verse.AI.JobDriver:TryActuallyStartNextToil()
Verse.AI.JobDriver:Verse.AI.JobDriver.ReadyForNextToil_Patch1(JobDriver)
Verse.AI.<>c__DisplayClass2_0:<DoRecipeWork>b__1()
Verse.AI.JobDriver:Verse.AI.JobDriver.DriverTick_Patch0(JobDriver)
Verse.AI.Pawn_JobTracker:Verse.AI.Pawn_JobTracker.JobTrackerTick_Patch0(Pawn_JobTracker)
Verse.Pawn:Verse.Pawn.Tick_Patch2(Pawn)
Verse.TickList:Tick()
Verse.TickManager:Verse.TickManager.DoSingleTick_Patch2(TickManager)
Verse.TickManager:Verse.TickManager.TickManagerUpdate_Patch1(TickManager)
Verse.Game:Verse.Game.UpdatePlay_Patch2(Game)
Verse.Root_Play:Update()

I'm not sure if this is a mod compatibility thing or just a bug.