Editor crashes on closing the Editor while it is building all the assets and preparing to run the Test after clicking on"Run all in Player(StandaloneWindows64)"
Steps to Reproduce:

1. Open attached Project Crashteroids Starter
2. Open Windows > General > TestRunner
3. Select playmode in TestRunner Window
4. Click on Run all in Player(Standalone)
5. While executing Unit testing close the Unity Editor

Expected Result:
Unity Editor is closed

Actual Result:
Unity Editor crashes

Reproducible on: 2020.1.0a22, 2020.1.0a21, 2020.1.0a10

Working fine on: 2020.1.0a9, 2019.3.0f6, 2019.2.7f1, 2019.1.12f1,2018.4.17f1

Environment: Windows 10 only