Firebase function signInWithCustomToken undefined with Node.js
<p>So I've created a custom token as such</p>

<pre><code>const token = authRef.createCustomToken(options.userId, {
    app: appRootName,
    debug: !!options.debug
});
</code></pre>

<p>And then attempt to sign it in as such</p>

<pre><code>return authRef.signInWithCustomToken(token).then((user) =&gt; {
    return user;
});
</code></pre>

<p>Custom creation token succeeds, but signInWithCustomToken spits out this error.</p>

<pre><code>TypeError: authRef.signInWithCustomToken is not a function
</code></pre>

<p>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?</p>