Navigator credentials creation method returning an exception

Question

Trying to run a demo for the webautn spec (https://www.w3.org/TR/webauthn/) available (https://github.com/molekilla/webauthn-demo-fork) under Firefox Nightly.

getMakeCredentialsChallenge({
        username,
        name
    })
    .then((response) => {
        console.log(response);

        let publicKey = preformatMakeCredReq(response);

        console.log(publicKey);

        console.log(publicKey.challenge)

        return navigator.credentials.create({publicKey})
    })

Whenever the execution reaches the return statement, the Promise will stay pending for a few seconds and eventually rejects, logging either [Exception... "Abort" nsresult: "0x80004004 (NS_ERROR_ABORT)" location: "<unknown>" data: no] or UnknownError: The operation failed for an unknown transient reason. Both objects seem fine. Any idea about the reason why is it not resolving?

Tabathatabb

Have you tried using Chrome 70, just to check? The demo works for me using Android phone + Chrome 70 – Potency