How to reproduce:
1. Open the attached "1066513_repro.zip" project
2. Open the "Main" scene
3. Enter Play mode
4. Select the "Director" GameObject from the Hierarchy
5. In the Timeline window, press Play
6. After the sound effect finishes, exit the Play mode
-- Editor crash

Reproducible with - 2018.2.0a4, 2018.2.2f1, 2018.3.0a7
Not reproducible with - 2017.1.0b7, 2017.1.5f1, 2017.2.3p2, 2017.4.8f1, 2018.1.0a1, 2018.1.9f1, 2018.2.0a3

Stack trace:
(Unity) AudioSource::Stop
(Unity) AudioManager::StopSources
(Unity) PlayerLoopController::ExitPlayMode
(Unity) PlayerLoopController::SetIsPlaying
(Unity) Application::TickTimer
(Unity) MainMessageLoop
(Unity) WinMain
(Unity) __scrt_common_main_seh
(KERNEL32) BaseThreadInitThunk
(ntdll) RtlUserThreadStart

Fixed in 2018.3.0a9