DropShadow with radius=0 in a delegate with required property causes a crash

In a simple example where ListView has a delegate which contains a required property and a DropShadow with a radius set to 0.0 crashes when the application is shut down.

Either changing the radius to 0.001 (or some other value above 0) OR removing the required property solves the problem.

Steps to reproduce the problem.

• Run the attached example
• Close the attached example