LogIn with Facebook

I am trying to get LogIn with Facebook to work but it isn't getting an Access Token.

I have pinned it down to this function in FacebookRedirectLoginHelper.php



 

Code:

public function getAccessToken($redirectUrl = null)
    {
     
        if (!$code = $this->getCode()) {
            return null;
        }


        $this->validateCsrf();

        $redirectUrl = $redirectUrl ?: $this->urlDetectionHandler->getCurrentUrl();
        // At minimum we need to remove the state param
        $redirectUrl = FacebookUrlManipulator::removeParamsFromUrl($redirectUrl, ['state']);

        return $this->oAuth2Client->getAccessTokenFromCode($code, $redirectUrl);
    }

It is  returning from

Code:

if (!$code = $this->getCode()) {
   return null;
}

with null

The code has me confused - where should getCode get the access code from to start with?


Thanks