To reproduce:
1. Open user's attached project, scene CrashScene
2. Enter Play mode

Expected: editor does not crash
Actual: editor crashes when DestroyOutput() is called

Reproduced in: 2017.1.3f1, 2017.2.1p2, 2017.3.0p2, 2018.1.0a7
Not reproduced in: 2018.1.0b1, 2018.1.0b3

Crash stack trace:
0x00000001418A788C (Unity) Animator::SetupPlayableConstant
0x00000001418978B1 (Unity) Animator::CreateBindings
0x0000000141897B8D (Unity) Animator::CreateObject
0x00000001418A0DA1 (Unity) Animator::Prepare
0x00000001418AA03C (Unity) Animator::UpdateAvatars
0x00000001407511D9 (Unity) DirectorManager::ExecuteStage
0x000000014075176F (Unity) `DirectorManager::InitializeClass'::`2'::PreLateUpdateDirectorUpdateAnimationBeginRegistrator::Forward
0x0000000140A0F97B (Unity) ExecutePlayerLoop
0x0000000140A0FA44 (Unity) ExecutePlayerLoop
0x0000000140A126DC (Unity) PlayerLoop
0x00000001414903A7 (Unity) PlayerLoopController::UpdateScene
0x0000000141481CF7 (Unity) PlayerLoopController::EnterPlayMode
0x000000014148D748 (Unity) PlayerLoopController::SetIsPlaying
0x000000014148F93E (Unity) Application::TickTimer
0x00000001416914F1 (Unity) MainMessageLoop
0x00000001416934DE (Unity) WinMain
0x00000001427DC0E7 (Unity) __scrt_common_main_seh
0x00007FFCEB781FE4 (KERNEL32) BaseThreadInitThunk
0x00007FFCEE05EFB1 (ntdll) RtlUserThreadStart