Hello,here I have a question ,in the game "A3GPU06_SlidingPuzzle", SlidingPuzzle.as ,if I change the numShuffle to be a smaller uint,for example:
// random shuffle steps
static const numShuffle:int = 3;
(to do this ,just convenient to test it)

when I quickly click the last puzzle before the puzzle which is the last but one completes its steps,then the bug arises:

TypeError: Error #1009: 无法访问空对象引用的属性或方法。
at SlidingPuzzle/puzzleComplete()
at SlidingPuzzle/slideDone()
at flash.events::EventDispatcher/flash.events:EventDispatcher::dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at flash.utils::Timer/flash.utils:Timer::tick()

Hope to helping me!