Crash when processing hover events modifies object tree

Breakdown of the issue, which can be reproduces with the attached project:

https://github.com/qt/qtdeclarative/blob/5a762ba09cdeb8df5cf54ce562bc60dfcc11c97f/src/quick/util/qquickdeliveryagent.cpp#L1007

The function above iterates over “hoverItems”:

https://github.com/qt/qtdeclarative/blob/5a762ba09cdeb8df5cf54ce562bc60dfcc11c97f/src/quick/util/qquickdeliveryagent_p_p.h#L76C5-L76C53

If the current “hoverId” does not match it can make a call to "deliverHoverEventToItem" here:

https://github.com/qt/qtdeclarative/blob/5a762ba09cdeb8df5cf54ce562bc60dfcc11c97f/src/quick/util/qquickdeliveryagent.cpp#L1053

This function can have side effects, example a mouse area closes the current window synchronously on a hover leave event.
The close event triggers a hide, which in turn calls “clearHover()” here:
https://github.com/qt/qtdeclarative/blob/5a762ba09cdeb8df5cf54ce562bc60dfcc11c97f/src/quick/util/qquickdeliveryagent.cpp#L1345

Which clears the flatmap that is currently being iterated over.
It returns from this point:

https://github.com/qt/qtdeclarative/blob/5a762ba09cdeb8df5cf54ce562bc60dfcc11c97f/src/quick/util/qquickdeliveryagent.cpp#L1053

And attempts to erase the iterator, which is now invalid, corrupting the flatmap which may continue iterating.