Sending certain key events to QQuickView showing a focused QtWebEngine causes crash

Reproducer attached. Steps to reproduce:
1. Run the sample and a WebEngineView with 4 arrows (Images with MouseArea above actually) is shown.
2. Click the WebEngineView (not the arrows) so that WebEngineView is focused.
3. Click left/right/down arrow will cause the program to crash. Very strangely, clicking up arro will not crash the program. Also, if not click WebEngineView first, clicking any arrow won't crash the program.

Haven't tested all key events. But here are some other cases:
Key events that crash the program: CapsLock, Backspace, Escape
Key events that do not crash the program: Control, Shift, Alt
So I don't see any pattern here. The key events are sent from settings.cpp and they can be modified to test other cases.

Clicking arrows does nothing but call C++ APIs and send the corresponding key events to QQuickView. I have commented out all unnecessary codes in the original reproducer.