Fix incorrect glyphicon name

src/main/resources/templates/fragments/layout.html

@@ -59,7 +59,7 @@
                       <span>Veterinarians</span>
                   </li>
   
-                  <li th:replace="::menuItem ('/oups','error','trigger a RuntimeException to see how it is handled','th-warning-sign','Error')">
+                  <li th:replace="::menuItem ('/oups','error','trigger a RuntimeException to see how it is handled','warning-sign','Error')">
                       <span class="glyphicon glyphicon-warning-sign" aria-hidden="true"></span>
                       <span>Error</span>
                   </li>