Qt 3D: Simple Custom Material QML example crashes

In the Qt 3D: Simple Custom Material QML example, if you resize the application window such that the vertical height is the smallest, and then try to expand the application window vertically again, the application will freeze. If you then try to close the application, it will crash.

Steps to reproduce:

1. Run the example.
2. Make the application window as small as possible vertically.
3. Make the application window larger vertically. Notice that the application freezes.
4. Try to close the application. Notice that the application crashes.