1. What happened
[OS X] Visual Studio crashes Editor when quitting with debugger attached
VS for Mac Community, v 7.0.1b24.
Attached debugger to the Editor, using 'Attach to process...' dialogue. After performing 'Quit' from VS, with the debugger still attached, Editor went down as well.

2. How we can reproduce it using the example you attached
- Open TestScript.cs in VS
- Run main menu > Attach to process... > Unity
- Quit VS
>>> Editor crashes with no messages/errors/...

Note: If VS starts debugging with 'Play' for UnityEditor debug configuration, then Quit suggests proper 'Let's stop debugging' message and no crash occurs.

Same behavior in 2017.1.0p2, 2017.2.0b5, 2017.3.0a2