title: Firebase app initialization fails with invalid-credential (firebase function initiatlization)
body: <p>As per <a href="https://firebase.google.com/docs/admin/setup#initialize_the_sdk" rel="noreferrer">the documentation</a>:</p>
  
  <p><em>If you are using the Node.js Admin SDK in a Cloud Function, you can automatically initialize the SDK through the functions.config() variable:</em></p>
  
  <pre><code>admin.initializeApp(functions.config().firebase);
  </code></pre>
  
  <p>But when I try this very simple piece of code:</p>
  
  <pre><code>const functions = require('firebase-functions')
  const admin = require('firebase-admin')
  
  admin.initializeApp(functions.config().firebase)
  
  exports.orhub = functions.https.onRequest((req, res) =&gt; {
      res.end()
  })
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>error: FIREBASE WARNING: {"code":"app/invalid-credential","message":"Credential implementation provided to initializeApp() via the \"credential\" property failed to fetch a valid Google OAuth2 access token with the following error: \"Error fetching access token: invalid_grant (Bad Request)\". There are two likely causes: (1) your server time is not properly synced or (2) your certificate key file has been revoked. To solve (1), re-sync the time on your server. To solve (2), make sure the key ID for your key file is still present at https://console.firebase.google.com/iam-admin/serviceaccounts/project. If not, generate a new key file at https://console.firebase.google.com/project/_/settings/serviceaccounts/adminsdk."}
  </code></pre>
  
  <p>My Ubuntu pc has date and timezone automatically synced, so that's not the problem. I created this project today, so I got the latest modules.</p>
  
  <p>So, what's the problem? Isn't "Cloud Functions" mentioned in the docs the same as Firebase functions?</p>