title: Authentication failed! Facebook returned an invalid user id on Yith social login wordpress
body: <p>Anyone can help me to solve this problem? I am using yith woocommerce social login plugin on my wordpress. I tried to implement login via facebook and g+. While using g+ login it's successfully work, but while using facebook there is no response and my page just reload my page and append this </p>
  
  <pre><code>#_=_
  </code></pre>
  
  <p>character into my url. </p>
  
  <p>plugins/yith-woocommerce-social-login/logs/log.txt show report below</p>
  
  <blockquote>
    <p>Hybrid_Auth initialize: A stored Error found, Throw an new Exception
    and delete it from the store: Error#5, 'Authentication failed!
    Facebook returned an invalid user id.' --</p>
  </blockquote>
  
  <p>wp_content/debug.log show report below</p>
  
  <blockquote>
    <p>PHP Fatal error:  Call to a member function authenticate() on null in
    /wp-content/plugins/yith-woocommerce-social-login/includes/class-yith-social-login.php
    on line 156</p>
  </blockquote>