Using the Google People API with Cloud Functions for Firebase

I'm trying to get a contact list from the Google People Cloud API for Firebase, but I only get an empty object as a response. Any thoughts? Cloud function code below:

var functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

var google = require('googleapis');
var people = google.people('v1');

exports.contacts = functions.https.onRequest((request, response) => {
  admin.database().ref('/settings/contacts/credentials/serviceAccount').once("value", function(data) {
    var authClient = new google.auth.JWT(
      data.child('clientEmail').val(),
      null,
      data.child('privateKey').val(),
      ['https://www.googleapis.com/auth/contacts'],
      null
    );

    authClient.authorize(function (err, tokens) {
      if (err) {
        console.error(err);
        response.end();
        return;
      }

      // Make an authorized request to list contacts.
      people.people.connections.list({auth: authClient, resourceName: 'people/me'}, function(err, resp) {
        if (err) {
          console.error(err);
          response.end();
          return;
        }

        console.log("Success");
        console.log(resp);
        response.send(resp);
      });

    });
  });

});

      

        
        
        
      

    

In the Firebase console logs, the success message is printed along with an empty JSON object. It seems to login successfully, so not really sure what's going on. Any help would be greatly appreciated.