error

When i open the pages
[url]
http://gamos.mobi/index.php/nyfika-gamo ... -2017-2018[/url]

or
[url]
http://gamos.mobi/index.php/nyfika-gamo ... -2017-2018[/url]

appears the Error Message
Notice: Trying to get property of non-object in /var/www/vhosts/adapokrites.gr/gamos/libraries/joomla/factory.php on line 223

can help you please

Thank i solved this !
i Replaced code this code


public static function getUser($id = null)
{
jimport('joomla.user.user');

if (is_null($id))
{
$instance = JFactory::getSession()->get('user');
if (!$instance INSTANCEOF JUser) {
$instance = &JUser::getInstance();
}
}
else
{
$instance = &JUser::getInstance($id);
}

return $instance;
}



to factory php