infinito/application/templates/frames/structure/message/flash_messages.html.twig

{% set icons = {'success':'fas fa-check-circle','danger':'fas fa-times','warning':'fas fa-exclamation-triangle','info':'fas fa-info'} %}
{% for label,messages in app.flashes %}
{% for message in messages %}
<div class="alert alert-{{ label }}">
	<i class="{{ icons[label] }}"></i> {{ message }}
</div>
{% endfor %}
{% endfor %}