So I've created a custom token as such

```
const token = authRef.createCustomToken(options.userId, {
    app: appRootName,
    debug: !!options.debug
});

```

And then attempt to sign it in as such

```
return authRef.signInWithCustomToken(token).then((user) => {
    return user;
});

```

Custom creation token succeeds, but signInWithCustomToken spits out this error.

```
TypeError: authRef.signInWithCustomToken is not a function

```

This is Firebase 3 for nodejs and the service account has been set up. The app was properly initialized (or token generation wouldn't work in the first place), what's the issue here?