Music Lab Shared Piano collaboration fails due to "Failed to construct 'RTCPeerConnection'"

[jengler]

The musiclab deployment at https://musiclab.chromeexperiments.com/Shared-Piano/#1xOCIHR0l has stopped working for collaborative play. Peer connection fails with the following exception:

Uncaught DOMException: Failed to construct 'RTCPeerConnection': 'stun:global.stun.twilio.com:3478?transport=udp' is not a valid stun or turn URL.
    at new _ (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4276:2029)
    at N (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4298:1317)
    at I (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4298:1265)
    at https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4298:3701
    at https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4194:46747
    at U (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4194:5691)
    at e.raise (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4194:102935)
    at e.raiseQueuedEventsMatchingPredicate_ (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4194:102550)
    at e.raiseEventsForChangedPath (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4194:102265)
    at e.onDataUpdate_ (https://musiclab.chromeexperiments.com/Shared-Piano/src.e9d99162.js:4194:142284)