I'm mostly just curious as to why this would happen, but whenever I have these two mods (Misc Robots ++: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=747645520 ), any time a construction robot builds an item of furniture, the furniture disapears, no resources are refunded, and this error gets thrown:
"""
Exception in Tick (pawn=Builder Bot (Tier 4), job=FinishFrame A=Thing_DoubleBed_Frame101171, CurToil=2): System.NullReferenceException: Object reference not set to an instance of an object
at RimWorld.CompArt.JustCreatedBy (Verse.Pawn pawn) [0x00000] in <filename unknown>:0
at RimWorld.Frame.CompleteConstruction (Verse.Pawn worker) [0x00000] in <filename unknown>:0
at RimWorld.JobDriver_ConstructFinishFrame+<MakeNewToils>c__IteratorE.<>m__34 () [0x00000] in <filename unknown>:0
at Verse.AI.JobDriver.DriverTick () [0x00000] in <filename unknown>:0 lastJobGiver=AIRobot.X2_JobGiver_Work, curJob.def=FinishFrame, curDriver=RimWorld.JobDriver_ConstructFinishFrame
Verse.Log:Error(String)
Verse.AI.Pawn_JobTracker:StartErrorRecoverJob(String)
Verse.AI.JobDriver:DriverTick()
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()
"""

I've already brought it up with the mod author on the other end, but I'm curious if you can figure out whats going on there.
Cheers~