How to reproduce:
1. Open user's attached project "LabsShadowmask.zip"
2. Enter the play mode (wait for the animation to begin)
3. Exit the play mode
-- Crash occurs

Reproducible with: 2018.3.0a6
Not reproducible with: 2017.1.5f1, 2017.2.3p2, 2017.4.8f1, 2018.1.9f1, 2018.2.1f1,2018.3.0a5

Note: I was able to reproduce the crash only with 2018.3.0a6. The crash is not 100% reproducible, I have reproduced it 3 times out of 12. First three lines of the stack trace and Editor.log error.log and crash.dmp files are in the description down below.