Crash when destroying child window

In 6.6 on Android 13, when the window is removed from the screen's stack, it loops through the remaining windows in the stack. the looping through the stack can have some nasty surprises at that point, since

1. the screen has a list of platform windows
2. it accesses their matching QWindows via window(), to read the flags of the QWindow
3. and, in QWindow::flags(), we access the platform window via d->platformWindow

And it seems in some cases it's possible we have a reference to a platform window in the screen's stack, but either the pointer returned by window(), or d->platformWindow member of that pointer, are not valid anymore.

This is working in 6.7/dev