Steps to reproduce:
1. Open User-supplied project
2. Open Scene "Sample Scene"
3. Enter and exit the Play mode a couple of times

Reproduced in: 2019.1.0a10, 2019.2.0a14, 2019.3.0a1
Not reproduced in: 2017.4.26f1, 2018.3.14f1, 2018.4.0f1, 2019.1.0a1, 2019.1.0a9

Note:
Can't enter Play mode
The game usually crashes on the third play

*Required package reset to enter play mode, that could have impacted the reproducibility

2019.1.0a1 Package Reversion:
Before: Can't check, Packman errors prevent me from opening the PackMan Window.
After: Ads: 2.0.8; Analytics: 3.0.9; IAP: 2.0.1; PackManUI: 2.0.0-preview.7; TMPro: 1.3.0; Collab: 1.2.9;

2018.4.0f1 Package Reversion:
Before: Can't check, Packman errors prevent me from opening the PackMan Window.
After: Ads: 2.0.8; Analytics: 3.2.2; IAP: 2.0.3; PackManUI: 2.0.7; TMPro: 1.3.0; Collab: 1.12.15;

2018.3.14f1 Package Reversion:
Before: Can't check, Packman errors prevent me from opening the PackMan Window.
After: Ads: 2.0.8; Analytics: 3.2.2; IAP: 2.0.3; PackManUI: 2.0.7; TMPro: 1.3.0; Collab: 1.12.15;

2017.4.26f1 No PackMan, could not test