How to reproduce:
1. Download and open attached project files
2. Open "TestScript" with Visual Studio Code (vscode) (Make sure .Net 4.6 is set in Player settings)
3. In vscode start debugging and Play Scene in Unity
4. In vscode stop debugging and Stop Scene in Unity
5. Editor freeze

Expected result: Unity shouldn't freeze
Actual result: As long as the debugger is attached, editor remains stable. If you detach debugger while playing scene, editor become freeze after you stop playing scene

Reproduced with: 2017.1.0b1, 2017.1.0f1, 2017.1.0p4, 2017.2.0b8, 2017.3.0a5