Crash in widgets application when setting style sheet on receiving mouse move in QWidget::event() with mouse tracking

The program crash on QApplication::quit().
I am not sure where is the problem exactly, but I have isolated the problem in a small example.

Basically, I made a window with 2 QWidget inside. QWidgets has mouse tracking enabled to set hover styling with QEvent::MouseMove.
On of the 2 inner QWidget trigger the application quit().

When I click on the border of one of them, the application crash.

Note: In the attached example, make sure cursor is within app window on start, do not move the cursor, it point to the specific position that make the program to crash.