Steps to reproduce:
1. Open attached project.
2. Enter the Play mode.

Actual result:
Unity Editor freezes (becomes unresponsive). If it does not freeze, try entering the Play mode several times and the Editor should crash.

Expected result:
The Editor should not freeze/crash when using private Profile and assigning it to null.

Note:
The script that seems to be causing this issue is named "ProfileItem" ("Assets->Scripts->UI->Screens->Profile").

Reproduced with:
5.3.5f1, 5.3.5p4, 5.4.0b22.

Cannot reproduce with:
5.1.0f3, 5.2.4f1, because Scene Management was not supported.