I want to know under what conditions this error occurs in Verse.

This is the problematic function indicated by the error statement. No problems have been found so far.

LogVerse: Error: VerseRuntimeErrors: Verse unrecoverable error: ErrRuntime_InvalidVarRead: Attempted to read a var out of an invalid object.
Truncated callstack follows:
task_GameManager$GenarateUIStart(:Generation,:agent,:GenerateChairData):Update (Unknown source) (Source: Unknown(0,0, 0,0))

GenarateUIStart(Generator : Generation,Agent : agent,SeatData : GenerateChairData)<suspends>:void=
        Print("GenerateStart",?Color := NamedColors.Yellow)
        if(set PlayerDatas[Agent].PlayerState = State.Generate):
        var EventCount : int = 0
        var CheckNow : logic = false
        GenerateSound.Play(Agent)
        race:
            loop:
                Ag := MoveXCheck.PressedEvent.Await()
                if(Ag = Agent){break}
            loop:
                Ag := MoveYCheck.PressedEvent.Await()
                if(Ag = Agent){break}
            loop:
                Ag := JumpCheck.PressedEvent.Await()
                if(Ag = Agent){break}
            loop:
                Sleep(0.1)
                Generator.AddEnergy(0.18)
                Size := (Generator.NowEnergy/100.0)
                if(not Generator.IsGenerated[]):
                    VarUpdate(Agent,Size)
            loop:
                Sleep(GetRandomFloat(7.0,13.0))
                if(SK := SkillCheck[GetRandomInt(0,SkillCheck.Length - 1)]):
                    if(Movie := SK.Cinema[PlayerDatas[Agent].PlayerNumber]):
                        Movie.Play(Agent)
                        set CheckNow = true
                        NowTime := GetSimulationElapsedTime()
                        race:
                            loop:
                                Ag := ShotCheck.PressedEvent.Await()
                                if(Ag = Agent):
                                    break
                            Movie.StoppedEvent.Await()
                        Movie.Stop(Agent)
                        Difference := Abs(GetSimulationElapsedTime() - NowTime - SK.ActiveFrame*(1.0/30.0))
                        if(Difference <= 0.06):
                            Generator.AddEnergy(1.0)
                            Print("Great")
                            GreatSound.Play(Agent)
                        else if(Difference <= 0.15):
                            Print("OK")
                            OKSound.Play(Agent)
                        else:
                            Print("Miss")
                            MissSound.Play(Agent)
                            if(FortChar := Agent.GetFortCharacter[],FortChar.IsActive[],Generator.EffectPos.IsValid[]):
                                Angele := ReturnTan(Generator.EffectPos.GetTransform(),FortChar.GetTransform())
                                var PosIn : transform = Generator.EffectPos.GetTransform()
                                set PosIn.Rotation = MakeRotationFromYawPitchRollDegrees(Angele,0.0,0.0)
                                Generator.AddEnergy(-5.0)
                                Prop := SpawnProp(MissEffect,PosIn)(0)
                                if(p := Prop?):
                                    spawn{DeleteDelay(p,3.0)}
                                break
                        Print("Diffence = {Difference}")
                        set CheckNow = false
                    
            loop:
                Generator.Shake()
                Sleep(1.0)
            loop:
                Ag := DamageEvent.Await()
                if(Ag = Agent):
                    break
            Generator.SuccsessEvent.Await()
        if(not Generator.IsGenerated[]):
            SeatData.Button.Enable()
        if(CheckNow = true and not Generator.IsGenerated[]):
            MissSound.Play(Agent)
            if(FortChar := Agent.GetFortCharacter[],FortChar.IsActive[],Generator.EffectPos.IsValid[]):
                Angele := ReturnTan(Generator.EffectPos.GetTransform(),FortChar.GetTransform())
                var Pos : transform = Generator.EffectPos.GetTransform()
                set Pos.Rotation = MakeRotationFromYawPitchRollDegrees(Angele,0.0,0.0)
                Generator.AddEnergy(-5.0)
                Prop := SpawnProp(MissEffect,Pos)(0)
                if(p := Prop?):
                    spawn{DeleteDelay(p,3.0)}
        for(SK : SkillCheck):
            if(Movie := SK.Cinema[PlayerDatas[Agent].PlayerNumber]):
                Movie.Stop(Agent)
        GenerateSound.Stop(Agent)
        if(Chair := PlayerDatas[Agent].SeatChair?):
            Chair.Eject(Agent)
        VarHide(Agent)
        if(set PlayerDatas[Agent].SeatChair = false):
        Print("GenerateEnd",?Color := NamedColors.Yellow)
        if(PlayerDatas[Agent].PlayerHealth >= 1.0):
            if(set PlayerDatas[Agent].PlayerState = State.Free):
                Print("Free")
        return