Repeating rules are now required

app/assets/javascripts/events.js.coffee

@@ -14,8 +14,10 @@ $(document).on 'turbolinks:load', ->
     $(this).change ->
       if $(this).val() > 0
         $('.field.rule').show()
+        $('.field.rule input').attr 'required', 'required'
       else
         $('.field.rule').hide()
+        $('.field.rule input').removeAttr 'required'
 
   # Manage event tags edition
   $('#event_tags').each ->

app/assets/stylesheets/form.sass

@@ -100,6 +100,8 @@ input, textarea, select, a.button, .actions > button, .mce-tinymce, div.tagsinpu
   [type=radio]:checked + label
     color: black
     box-shadow: 0 0 0 6px lightgray
+  [type=radio]:invalid + label
+    box-shadow: 0 0 1px tomato
 
 .actions
   text-align: center

app/views/events/_form.html.haml

@@ -76,7 +76,7 @@
     .field.repeat{ title: t('.rule_helper') }
       = f.label :repeat
       = f.number_field :repeat, in: 0..40
-    .field.rule
+    .field.rule.required
       = f.label :rule
       %span.radios
         - Event::RULES.each do |rule|