Laravel 9 - Google Calendar API using google-api-php-client - Call to a member function listEvents() on null

I'm trying to enable and sync Google Calendar API in my project.

Summary:

In my current project i've multiple users and each user has a dashboard with fullcalendar.js. I've a table named events and it has these columns

Events
    name
    description
    user_id
    full_day
    start
    end

Users can create calendar events through a modal which i save in the database.

I want to enable the ability for the users to import their Google Calendar Events and/or 2-way sync events.

So far i've done the following:

1) Enabled calendar api, created OAuth Tokens for webapp (client id & secret), filled in redirect and created a google consent screen.

2) composer require google/apiclient in my project.

3) Setup Socialite Google drive

4) Created a controller named GoogleController and created routes for it.

1. OAuthGoogle method (GoogleController) with the following code:

public function OAuthGoogle()
    {
        $scopes = [
            'https://www.googleapis.com/auth/userinfo.email',
            'https://www.googleapis.com/auth/userinfo.profile',
            'openid',
            'https://www.googleapis.com/auth/calendar'
        ];

        return Socialite::driver('google')
            ->scopes($scopes)
            ->with(["access_type" => "offline", "prompt" => "consent select_account"])
            ->redirect();
    }

After that on the redirect Method i've the following code where i store the tokens in user DB:

public function OAuthGoogleCallback()
    {
        $user = Socialite::with('google')->user();

        $loggedUser = getAuthUser();

        $loggedUser->google_access_token = Crypt::encryptString($user->token);
        $loggedUser->google_refresh_token = Crypt::encryptString($user->refreshToken);
        $loggedUser->save();
    }

After that i'm trying to fetch calendar events and list them:

public function list()
    {

        $user = getAuthUser();
        $token = Crypt::decryptString($user->google_access_token);

        $client = new Google_Client();
        $client->setAccessToken($token);

        $service = new Calendar($client);

        // $calendarId = 'primary';
        $optParams = array(
            'maxResults' => 10,
            'orderBy' => 'startTime',
            'singleEvents' => true,
            'timeMin' => date('c'),
        );

        $events = $service->events->listEvents('primary');

        while (true) {
            foreach ($events->getItems() as $event) {
                echo $event->getSummary();
            }
            $pageToken = $events->getNextPageToken();
            if ($pageToken) {
                $optParams = array('pageToken' => $pageToken);
                $events = $service->events->listEvents('primary', $optParams);
            } else {
                break;
            }
        }
    }

Unfortunately I get the following error when I try it:

Call to a member function listEvents() on null

thanks in advance for your help!