title: Symfony2 Sonata Admin Error
body: <p>I recently did a vendors/install and now my sonata admin is broken with the following error:</p>
  
  <p>Item "roles" for "" does not exist in SonataAdminBundle::standard_layout.html.twig at line 92</p>
  
  <p>Here is the twig code:</p>
  
  <pre><code>{% if app.security %}
    {% for role in app.security.token.roles %}
      {% if not allowed %}
        {% set allowed = role.role == 'ROLE_SONATA_ADMIN' %}
      {% endif %}
    {% endfor %}
  {% endif %}
  </code></pre>
  
  <p>Anyone have any thoughts?</p>
  
  <p>Thanks!</p>