How to reproduce:
1. Open the "Entity_Repro.zip" project
2. Open the "SampleScene" scene
3. Open the test.cs in Rider
4. Attach debugger to Unity
5. Add breakpoint on line "int b = 5;" test.cs:27
6. Enter Play mode
7. When the breakpoint is hit, inspect "world.EntityManager" and expand it's evaluation (or clientWorlds[0] > EntityManager)
8. Exit the inspection and try to inspect it again
9. If "Evaluating..." appears exit the inspection and remove the breakpoint
10. Resume the program

Actual result: Unity freezes.

Reproducible with: 2020.1.a20, 2019.3.0f6.

Notes:
- Can't test 2019.2 and earlier because of package errors.