Implement image upload

templates/app/new_listing.html.twig

@@ -1,6 +1,12 @@
 {% extends 'base.html.twig' %}
 
 {% block body %}
+    {% for message in app.flashes('error') %}
+    <div class="alert alert-error" role="alert">
+        {{ message }}
+    </div>
+    {% endfor %}
+
     <h1 class="mb-3">Add new offering</h1>
     {{ form(offering_form) }}
 {% endblock %}