How to reproduce:
1. Open the attached project
2. In Project window, select the "Expozure.Engine" prefab from the Assets/Expozure/Prefabs folder

Expected result: Editor does not crash.
Actual result: Editor crashes.

Reproducible with - 2018.2.0x-ImprovedPrefabs (ff19e2e229d2)
Not reproducible with - 2017.1.4p2, 2017.2.3p1, 2017.4.6f1, 2018.1.6f1, 2018.2.0b9, 2018.3.0a3

Stack trace:
(mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\metadata\unity-liveness.c:190] mono_add_process_object
(mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\metadata\unity-liveness.c:355] mono_traverse_array
(mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\metadata\unity-liveness.c:304] mono_traverse_objects
(mono-2.0-bdwgc) [c:\buildslave\mono\build\mono\metadata\unity-liveness.c:522] mono_unity_liveness_calculation_from_root
(Unity) MarkDependencies
(Unity) GarbageCollectSharedAssets
(Unity) UnloadUnusedAssetsOperation::IntegrateMainThread
(Unity) PreloadManager::UpdatePreloadingSingleStep
(Unity) PreloadManager::WaitForAllAsyncOperationsToComplete
(Unity) Application::TickTimer
(Unity) MainMessageLoop
(Unity) WinMain
(Unity) __scrt_common_main_seh
(KERNEL32) BaseThreadInitThunk
(ntdll) RtlUserThreadStart

Fixed in 2018.3.0a6