about CCMenu issue (setHandlerPriority)

totay i involved a CCMenu method called “setHandlerPriority”,but my app crashed.
so i use breakpoint to debug.
i found that, because the method called “findHandler” in CCTouchDispatcher.cpp returned NULL, so this(CCAssert(handler != NULL, “”); can’t through.
but i use the same method by cocos2d-iphone, my app will never crash.
so i saw the source code , found that below codes isn’t in the same method of cocos2d-x
@
if (toAdd)
{
for( CCTouchHandler *handler in handlersToAdd )
{
if (handler.delegate == delegate)
{
return handler;
}
}
}
@

so, i want to ask why not to add these codes to cocos2d-x