The link to visualize was too relative, and sometimes it could fail in some...

The link to visualize was too relative, and sometimes it could fail in some specific cases (after a failed creation)

app/views/events/_form.html.haml

@@ -85,7 +85,7 @@
             t(rule, scope: 'activerecord.attributes.event.rule_values')
 
   .actions
-    = f.button formaction: :preview do
+    = f.button formaction: url_for(action: @event.new_record? ? :preview_create : :preview) do
       %em.fa.fa-eye
       = t '.visualise'