anchor.diff:                              | (false, _) ->
                                   let children = USet.singleton HashIdentity.Structural (World.getCollectionConfig world) entity
                                   let world = World.choose { world with EntityHierarchy = UMap.add parent children world.EntityHierarchy }
  -                                let world = World.setEntityIsParent true parent world |> snd'
  +                                let world = if World.getEntityExists parent world then World.setEntityIsParent true parent world |> snd' else world
                                   world
                           | None -> world
                       world
  
positive.code:             | (true, entityChangeCounts) -> if UMap.containsKey entityAddress entityChangeCounts then entityState.PublishChangeEvents <- true
              | (false, _) -> ()
  
              // add entity's state to world
              let entity = Entity entityAddress
              let world =
                  if World.getEntityExists entity world then
                      if World.getEntityDestroying entity world
  
negative.code:                                 let children = USet.remove entity children
                                  if USet.isEmpty children then
                                      let world = World.choose { world with EntityHierarchy = UMap.remove oldParent world.EntityHierarchy }
                                      let world = if World.getEntityExists oldParent world then World.setEntityIsParent false oldParent world |> snd' else world
                                      world
                                  else World.choose { world with EntityHierarchy = UMap.add oldParent children world.EntityHierarchy }
                              | (false, _) -> world
  