How do you extend view classes?

[Jaxel]

I have this listener:

<?php

class EWRporta_Listener_View
{
    public static function forumList($class, array &$extend)
    {
        if ($class == 'XenForo_ViewPublic_Forum_List')
        {
            $extend[] = 'EWRporta_ViewPublic_ForumList';
        }
    }
}

<?php

class EWRporta_ViewPublic_ForumList extends XFCP_EWRporta_ViewPublic_ForumList
{
    public function renderHtml()
    {
        $response = parent::renderHtml();
        return $response;
    }
}

As you can see, right now it doesn't do anything. However, when I enable the listener, instead of running properly, I get the following error:

Template Errors: PAGE_CONTAINER

1. Object of class stdClass could not be converted to string in /public_html/library/XenForo/Template/Abstract.php(262) : eval()'d code, line 712:
   711: <!-- main template -->
   712: ' . $contents . '
   713: