How to reproduce:
1. Open the attached project
2. Open the "default" scene
3. Press Play
4. Double click on any galaxy
5. Double click on any solar system
6. Holding RMB navigate the view so the orbit lane is visible (white line around)
7. Double click on a planet (should be on the orbit lane, if there is none, double-click and choose another solar system)
8. Reimport PlanetManagement.cs script
9. Switch tabs between Console and Project
10. If Unity didn't crash already, repeat 8-9

Actual result: Unity crashes.

Reproducible with: 2018.3.0a1, 2018.2.0b7, 2018.1.4f1, 2017.4.5f1, 2018.2.3f1, 2017.1.4p1.

Note: 2018.3.0a1, 2018.2.0b7 doesn't crash, but freezes.