{% if not formEntity.vars.valid %}
<div class="alert alert-danger" role="alert">
  {# Loop through every form item #}
  {% for child in formEntity.children|slice(0,1) %}
      {# Display one error #}
      {% if child.vars.errors|length > 0 %}
        <li>{{child.vars.errors.0.message}}</li>
      {% endif %}
      {# Display the errors of the form item 
      {% for error in child.vars.errors %}
          <li>{{error.message}}</li>
      {% endfor %} #}
  {%endfor%}
</div>
{% endif %}