UX: Wiggle invalid form elements. Don't allow a site title of Discourse

lib/wizard/builder.rb

@@ -30,7 +30,11 @@ class Wizard
         step.add_field(id: 'site_description', type: 'text', required: true, value: SiteSetting.site_description)
 
         step.on_update do |updater|
-          updater.apply_settings(:title, :site_description)
+          updater.ensure_changed(:title)
+
+          if updater.errors.blank?
+            updater.apply_settings(:title, :site_description)
+          end
         end
       end
 

lib/wizard/step_updater.rb

@@ -39,6 +39,10 @@ class Wizard
       errors.add(id, e.message)
     end
 
+    def ensure_changed(id)
+      errors.add(id, '') if @fields[id] == SiteSetting.defaults[id]
+    end
+
     def apply_settings(*ids)
       ids.each {|id| apply_setting(id)}
     end