add flashbag twig display condition + improve class consistency (main_search)

src/Bundle/ChillMainBundle/Resources/views/layoutWithVerticalMenu.html.twig

@@ -29,8 +29,9 @@
             <div class="col-md-9">
                 
                 {# Flash messages ! #}
-                <div class="mt-5">
-                    <div class="row justify-content-center">
+                {% if app.session.flashbag.all()|length > 0 %}
+                <div class="row justify-content-center mt-5">
+                    
                     {% for flashMessage in app.session.flashbag.get('success') %}
                         <div class="col-8 alert alert-success flash_message">
                             <span>{{ flashMessage|raw }}</span>
@@ -48,8 +49,9 @@
                             <span>{{ flashMessage|raw }}</span>
                         </div>
                     {% endfor %}
-                    </div>
+                    
                 </div>
+                {% endif %}
 
                 {% block layout_wvm_content %}<!-- content of the layoutWithVerticalMenu is empty -->
                 {% endblock  %}