Citizen not found Error spamming the output_log (PublicTransportTours)

[t1a2l]

Citizen not found!
at System.Environment.get_StackTrace()
at NetNode.RemoveTargetCitizen(UInt16 instanceID, CitizenInstance ByRef data)
at ResidentAI.SetTarget(UInt16 instanceID, CitizenInstance ByRef data, UInt16 targetIndex, Boolean targetIsNode)
at CitizenAI.SetTarget(UInt16 instanceID, CitizenInstance ByRef data, UInt16 targetBuilding)
at HumanAI.StartMoving_Patch1(System.Object , UInt32 , Citizen ByRef , UInt16 , UInt16 )
at HumanAI.StartMoving(UInt32 citizenID, Citizen ByRef data, UInt16 sourceBuilding, TransferOffer offer)
at ResidentAI.StartTransfer(UInt32 citizenID, Citizen ByRef data, TransferReason reason, TransferOffer offer)
at TransferManager.StartTransfer(TransferReason material, TransferOffer offerOut, TransferOffer offerIn, Int32 delta)
at TransferManager.MatchOffers_Patch1(System.Object , TransferReason )
at TransferManager.SimulationStepImpl(Int32 subStep)
at SimulationManagerBase`2.SimulationStep(Int32 subStep)
at TransferManager.ISimulationManager.SimulationStep(Int32 subStep)
at SimulationManager.SimulationStep()
at SimulationManager.SimulationThread() [Core]

IPT: Vehicles of item class [serrvice: PublicTransport, sub service: PublicTransportTours, level: Level5] were requested. None was found.