In an attempt to reproduce a failure in the Windows input audio implementation, I stopped the audio service on Windows. The failure getUserMedia returned was TypeError, with the message "At least one of audio and video must be requested"[1]. I used appr.tc with audio only and echo cancellation disabled and the constraints looked fine (identical to when the service was started and gUM was successful).

I had also added a log line in UserMediaRequest::Fail[2] which was printed with error 5 (DevicesNotFound).

1. Returning a TypeError is a bug, needs to be fixed.
2. How can the TypeError be returned while we end up with a DevicesNotFound failure?

[1] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/mediastream/UserMediaRequest.cpp?type=cs&l=385
[2] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/modules/mediastream/UserMediaRequest.cpp?type=cs&l=567