Bright threw exception in WorkGiver WorkGiverEtchWall: System.InvalidOperationException: Invalid ThingRequest ThingRequest(group Undefined)
  at Verse.ListerThings.ThingsMatching (ThingRequest req) [0x00000] in <filename unknown>:0
  at Verse.GenClosest.ClosestThingReachable (IntVec3 root, Verse.Map map, ThingRequest thingReq, PathEndMode peMode, TraverseParms traverseParams, Single maxDistance, System.Predicate`1 validator, IEnumerable`1 customGlobalSearchSet, Int32 searchRegionsMin, Int32 searchRegionsMax, Boolean forceGlobalSearch, RegionType traversableRegionTypes, Boolean ignoreEntirelyForbiddenRegions) [0x00000] in <filename unknown>:0
  at RimWorld.JobGiver_Work.TryIssueJobPackage (Verse.Pawn pawn, JobIssueParams jobParams) [0x00000] in <filename unknown>:0
Verse.Log:Error(String, Boolean)
RimWorld.JobGiver_Work:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_PrioritySorter:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_Priority:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_Tagger:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_Subtree:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.ThinkNode_Priority:TryIssueJobPackage(Pawn, JobIssueParams)
Verse.AI.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()
Verse.TickList:Tick()
Verse.TickManager:DoSingleTick()
Verse.TickManager:TickManagerUpdate()
Verse.Game:UpdatePlay()
Verse.Root_Play:Update()