Crash when audio device is unplugged and the audio mixer engine is in use

The Editor crashes when using the new audio mixer and adding/removing a USB headset to the PC.

1. Ensure that that there are two sets of headphones connected to the PC
   • One should be USB, the other using the audio jack
   • Disable all audio playback devices except for the USB headset
2. Enable the new audio mixer
   • \Engine\Config\Windows\WindowsEngine.ini
   •  AudioDeviceModuleName=AudioMixerXAudio2
3. Setup a project with PlatformerGame
4. Open up the PlatformerGame project and ensure the Platformer_StreetSection is picked
5. Launch PIE and get to a point where the robot begins running
6. Unplug and plug back in the USB headset around 4 or 5 times
7. Close out of PIE

Results: If the project did not crash while running PIE it will crash when exiting PIE

Expected: The project to continue running normally regardless of what audio devices is removed/added

LoginId:874423d847e4031245a25d82b6f3b390
EpicAccountId:6b50d04f360f4c7587a1171ba17d6a2a

Assertion failed: OutputAudioStreamMasteringVoice [Link Removed] [Line: 422]

UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:425]
UE4Editor_AudioMixerXAudio2!Audio::FMixerPlatformXAudio2::CloseAudioStream() [d:\build\++ue4\sync\engine\source\runtime\windows\audiomixerxaudio2\private\audiomixerplatformxaudio2.cpp:422]
UE4Editor_AudioMixer!Audio::FMixerDevice::TeardownHardware() [d:\build\++ue4\sync\engine\source\runtime\audiomixer\private\audiomixerdevice.cpp:276]
UE4Editor_Engine!FAudioDevice::Teardown() [d:\build\++ue4\sync\engine\source\runtime\engine\private\audiodevice.cpp:420]
UE4Editor_Engine!FAudioDeviceManager::ShutdownAudioDevice() [d:\build\++ue4\sync\engine\source\runtime\engine\private\audiodevicemanager.cpp:250]
UE4Editor_Engine!UGameViewportClient::BeginDestroy() [d:\build\++ue4\sync\engine\source\runtime\engine\private\gameviewportclient.cpp:281]
UE4Editor_CoreUObject!UObject::ConditionalBeginDestroy() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:934]
UE4Editor_CoreUObject!UnhashUnreachableObjects() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1625]
UE4Editor_CoreUObject!CollectGarbageInternal() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1576]
UE4Editor_CoreUObject!CollectGarbage() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\garbagecollection.cpp:1656]
UE4Editor_UnrealEd!UEditorEngine::EndPlayMap() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\playlevel.cpp:468]
UE4Editor_UnrealEd!UEditorEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorengine.cpp:1957]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedengine.cpp:403]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3495]
UE4Editor!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:144]
UE4Editor!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:223]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283]
kernel32
ntdll