[flexcoders] tile list animation / transition throws error when height shrinks(not always!)

[fotis.chatzinikos]

Hello all,

can anybody throw any pointer on this?

I have a tilelist (vertical/single column) with custom item renderer,
when i use a state to shrink its height (minimize like functionality)
sometimes i get the following error (note: SOMETIMES once every ... do
not know 5 times):

TypeError: Error #1009: Cannot access a property or method of a null
object reference.
        at mx.controls.listClasses::ListBase/addToFreeItemRenderers()
        at mx.controls.listClasses::ListBase/reduceRows()
        at mx.controls.listClasses::ListBase/updateDisplayList()
        at mx.controls.listClasses::TileBase/updateDisplayList()
        at mx.controls.listClasses::ListBase/validateDisplayList()
        at mx.managers::LayoutManager/validateDisplayList()
        at mx.managers::LayoutManager/doPhasedInstantiation()
        at mx.managers::LayoutManager/validateNow()
        at mx.effects::Tween$/timerHandler()
        at flash.utils::Timer/_timerDispatch()
        at flash.utils::Timer/tick()

TIA,
Fotis