Exception when feeding prisoners from a Nutrient dispenser

[DoctorVanGogh]

This is a bug in vanilla Rimworld, but it's only exposed when you install certain mods - so no idea if this is the right place or the Mods subsection.
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If you have pawns that are non-people who try to feed an incapacitated prisoner from a nutrient dispenser you get an error in the log on every job:

Code Select Expand


Exception in BreadthFirstTraverse: System.NullReferenceException: Object reference not set to an instance of an object
  at RimWorld.FoodUtility+<BestFoodSourceOnMap>c__AnonStorey259.<>m__1 (Verse.Thing t) [0x00000] in <filename unknown>:0
  at Verse.GenClosest+<RegionwiseBFSWorker>c__AnonStorey5FC.<>m__BFF (Verse.Region r) [0x00000] in <filename unknown>:0
  at Verse.RegionTraverser+BFSWorker.BreadthFirstTraverseWork (Verse.Region root, Verse.RegionEntryPredicate entryCondition, Verse.RegionProcessor regionProcessor, Int32 maxRegions, RegionType traversableRegionTypes) [0x00000] in <filename unknown>:0
  at Verse.RegionTraverser.BreadthFirstTraverse (Verse.Region root, Verse.RegionEntryPredicate entryCondition, Verse.RegionProcessor regionProcessor, Int32 maxRegions, RegionType traversableRegionTypes) [0x00000] in <filename unknown>:0
Verse.Log:Error(String)
Verse.RegionTraverser:BreadthFirstTraverse(Region, RegionEntryPredicate, RegionProcessor, Int32, RegionType)
Verse.GenClosest:RegionwiseBFSWorker(IntVec3, Map, ThingRequest, PathEndMode, TraverseParms, Predicate`1, Func`2, Int32, Int32, Single, RegionType, Boolean)
Verse.GenClosest:ClosestThingReachable(IntVec3, Map, ThingRequest, PathEndMode, TraverseParms, Single, Predicate`1, IEnumerable`1, Int32, Int32, Boolean, RegionType, Boolean)
RimWorld.FoodUtility:BestFoodSourceOnMap(Pawn, Pawn, Boolean, FoodPreferability, Boolean, Boolean, Boolean, Boolean, Boolean, Boolean, Boolean)
RimWorld.FoodUtility:TryFindBestFoodSourceFor(Pawn, Pawn, Boolean, Thing&, ThingDef&, Boolean, Boolean, Boolean, Boolean, Boolean)
RimWorld.WorkGiver_FeedPatient:HasJobOnThing(Pawn, Thing, Boolean)
AIRobot.<>c__DisplayClass1_1:<TryGiveJob>b__0(Thing)
Verse.<RegionwiseBFSWorker>c__AnonStorey5FC:<>m__BFF(Region)
Verse.BFSWorker:BreadthFirstTraverseWork(Region, RegionEntryPredicate, RegionProcessor, Int32, RegionType)
Verse.RegionTraverser:BreadthFirstTraverse(Region, RegionEntryPredicate, RegionProcessor, Int32, RegionType)
Verse.GenClosest:RegionwiseBFSWorker(IntVec3, Map, ThingRequest, PathEndMode, TraverseParms, Predicate`1, Func`2, Int32, Int32, Single, RegionType, Boolean)
Verse.GenClosest:ClosestThingReachable(IntVec3, Map, ThingRequest, PathEndMode, TraverseParms, Single, Predicate`1, IEnumerable`1, Int32, Int32, Boolean, RegionType, Boolean)
AIRobot.X2_JobGiver_Work:TryGiveJob(Pawn)
Verse.AI.ThinkNode_JobGiver:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_PrioritySorter:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_Priority:TryIssueJobPackage(Pawn, JobIssueParams)
RimWorld.ThinkNode_Conditional:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_Priority:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.Pawn_JobTracker:DetermineNextJob(ThinkTreeDef&)
Verse.AI.Pawn_JobTracker:TryFindAndStartJob()
Verse.AI.Pawn_JobTracker:JobTrackerTick()
Verse.Pawn:Tick()
AIRobot.X2_AIRobot:Tick()
Verse.TickList:Tick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()

While there's non vanilla code in the stack trace, the bug itself is completely from the base game.

RimWorld.FoodUtility+<BestFoodSourceOnMap>c__AnonStorey259.<>m__1 (or in non-decompiled source, just the RimWorld.FoodUtility.BestFoodSourceOnMap method) contains code near the bottom of:

...
Predicate<Thing> predicate = (Thing t) => foodValidator(t) && !FoodUtility.filtered.Contains(t) && t.def.ingestible.preferability > FoodPreferability.DesperateOnly && !t.IsNotFresh();
Predicate<Thing> validator = predicate;
bool ignoreEntirelyForbiddenRegions = flag;
thing = GenClosest.ClosestThingReachable(getter.Position, getter.Map, thingRequest, PathEndMode.ClosestTouch, TraverseParms.For(getter, Danger.Deadly, TraverseMode.ByPawn, false), 9999f, validator, null, 0, searchRegionsMax, false, RegionType.Set_Passable, ignoreEntirelyForbiddenRegions);
...

If the feeding pawn is a person this line never seems to be reached, the code exits early. With non-person pawns this check is run, and subsequently blows, since it's invoked with a Nutrient dispenser for the Thing - which has no ingestible, so access to it's preferability blows.

A simple fix would be a change of the highlighted piece to t.def.ingestible?.preferability > FoodPreferability.DesperateOnly to prevent any errors. But probably there's a substitution to the dispensed nutrient meal's properties intended there, like in earlier parts of the method.

Demo savegame (needs Miscellaneous 'CORE', Misc. Robots & Misc. Robots++): https://drive.google.com/open?id=0B2GJ6pU1K8cKYldGTTY0bXctYlE

Just hit the Activate gizmo on the ER bot to awake it and have it start the feeding jobs and trigger the error.


Offtopic: This contains a bare minimum savegame with a 5% world as an ultra compression 620kb 7zip.... How is this supposed to fit in 600kb as an attachment?

Moderator's edit (Calahan)

How is this supposed to fit in 600kb as an attachment?

By using some 7zip wizardry to get it down to 540kb  

[attachment deleted by admin due to age]

[ison]

I think it happens for pawns who are RaceProps.ToolUser but aren't RaceProps.Humanlike. Fixed, thanks.