PHP Google People API - Simple email request failing - php

Question

Thank you everyone for your time.
I've spent all day on this although, wasn't able to find a good example and answer, so I thought it may be relevant for the community.
<?php
session_start();
require_once ('Google/src/Google/autoload.php');
$client = new Google_Client();
$client->setApplicationName("xxxxx");
$client->setClientId('xxxxx');
$client->setClientSecret('xxxxx')
$client->setRedirectUri('xxxxx');
$client->addScope('profile');
$client->addScope('email');
$client->addScope('https://www.googleapis.com/auth/contacts.readonly');
if (isset($_GET['oauth'])) {
// Start auth flow by redirecting to Google's auth server
$auth_url = $client->createAuthUrl();
header('Location: ' . filter_var($auth_url, FILTER_SANITIZE_URL));
} else if (isset($_GET['code'])) {
// Receive auth code from Google, exchange it for an access token, and redirect to your base URL
$client->authenticate($_GET['code']);
$_SESSION['access_token'] = $client->getAccessToken();
$redirect_uri = 'http://' . $_SERVER['HTTP_HOST'] . '/';
header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL));
} else if ($_SESSION['access_token']) {
// You have an access token; use it to call the People API
$client->setAccessToken($_SESSION['access_token']);
$service = new Google_Service_People($client);
$optParams = array('pageSize' => 10);
// TODO: Use service object to request People data
$results = $service->people_connections->listPeopleConnections('people/me', $optParams);
} else {
$redirect_uri = 'http://' . $_SERVER['HTTP_HOST'] . '/?oauth';
header('Location: ' . filter_var($redirect_uri, FILTER_SANITIZE_URL));
}
Upon executing the script I simply get a blank white page, if I comment out $results = $service->people_connections->listPeopleConnections('people/me', $optParams) the script then works.
It looks like it loads the API properly and authenticates with Oauth and the token session variables are set; although when uncommented it is simply a white screen so I think the problem is retrieving data from the Google People API.
I'm trying to download a list of each users contacts (including name & email) to share a link with via email; after clicking a 'Login with Google' button.
Any assistance would be greatly appreciated, thank you for your time!