JobDriver threw exception in toil MakeSolidThingFromBlueprintIfNecessary's initAction for pawn VanLue driver=JobDriver_PlaceNoCostFrame (toilIndex=2) driver.job=(PlaceNoCostFrame (Job_60733) A = Thing_Blueprint_SCM_SandCastle28042 Giver = JobGiver_Work [workGiverDef: ConstructDeliverResourcesToBlueprints])
System.NullReferenceException: Object reference not set to an instance of an object
[Ref 44484BFE] Duplicate stacktrace, see ref for original
UnityEngine.StackTraceUtility:ExtractStackTrace ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Log.Error_Patch5 (string)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.JobUtility.TryStartErrorRecoverJob_Patch2 (Verse.Pawn,string,System.Exception,Verse.AI.JobDriver)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.JobDriver.TryActuallyStartNextToil_Patch0 (Verse.AI.JobDriver)
Verse.AI.JobDriver:ReadyForNextToil ()
Verse.AI.Toils_Goto/<>c__DisplayClass5_0:<MoveOffTargetBlueprint>b__0 ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.JobDriver.TryActuallyStartNextToil_Patch0 (Verse.AI.JobDriver)
Verse.AI.JobDriver:ReadyForNextToil ()
Verse.AI.JobDriver:Notify_PatherArrived ()
Verse.AI.Pawn_PathFollower:PatherArrived ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.Pawn_PathFollower.StartPath_Patch3 (Verse.AI.Pawn_PathFollower,Verse.LocalTargetInfo,Verse.AI.PathEndMode)
Verse.AI.Toils_Goto/<>c__DisplayClass1_0:<GotoThing>b__0 ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.JobDriver.TryActuallyStartNextToil_Patch0 (Verse.AI.JobDriver)
Verse.AI.JobDriver:ReadyForNextToil ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.Pawn_JobTracker.StartJob_Patch3 (Verse.AI.Pawn_JobTracker,Verse.AI.Job,Verse.AI.JobCondition,Verse.AI.ThinkNode,bool,bool,Verse.ThinkTreeDef,System.Nullable`1<Verse.AI.JobTag>,bool,bool,System.Nullable`1<bool>,bool,bool,bool)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.Pawn_JobTracker.TryFindAndStartJob_Patch1 (Verse.AI.Pawn_JobTracker)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.Pawn_JobTracker.EndCurrentJob_Patch2 (Verse.AI.Pawn_JobTracker,Verse.AI.JobCondition,bool,bool)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.AI.Pawn_JobTracker.JobTrackerTick_Patch0 (Verse.AI.Pawn_JobTracker)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Pawn.Tick_Patch1 (Verse.Pawn)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.TickList.Tick_Patch2 (Verse.TickList)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.TickManager.DoSingleTick_Patch3 (Verse.TickManager)
Verse.TickManager:TickManagerUpdate ()
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Game.UpdatePlay_Patch1 (Verse.Game)
(wrapper dynamic-method) MonoMod.Utils.DynamicMethodDefinition:Verse.Root_Play.Update_Patch0 (Verse.Root_Play)

Pawns will try to "rebuild" the sand castles when it generates a blueprint after crumbling, but it's impossible so they're just standing and producing errors
Seems to happen when certain mod combinations are enabled, but I'm not sure which is causing cross-mod issues