Better username change validation messages

app/assets/javascripts/discourse/controllers/preferences_username_controller.js.coffee

@@ -1,18 +1,18 @@
 Discourse.PreferencesUsernameController = Ember.ObjectController.extend Discourse.Presence,
 
   taken: false
-  invalid: false
   saving: false
   error: false
+  errorMessage: null
 
   saveDisabled: (->
     return true if @get('saving')
     return true if @blank('newUsername')
     return true if @get('taken')
-    return true if @get('invalid')
     return true if @get('unchanged')
+    return true if @get('errorMessage')
     false
-  ).property('newUsername', 'taken', 'invalid', 'unchanged', 'saving')
+  ).property('newUsername', 'taken', 'errorMessage', 'unchanged', 'saving')
 
   unchanged: (->
     @get('newUsername') == @get('content.username')
@@ -20,12 +20,12 @@ Discourse.PreferencesUsernameController = Ember.ObjectController.extend Discours
 
   checkTaken: (->
     @set('taken', false)
-    @set('invalid', false)
+    @set('errorMessage', null)
     return if @blank('newUsername')
     return if @get('unchanged')
     Discourse.User.checkUsername(@get('newUsername')).then (result) =>
       if result.errors
-        @set('invalid', true)
+        @set('errorMessage', result.errors.join(' '))
       else if result.available == false
         @set('taken', true)
   ).observes('newUsername')

app/assets/javascripts/discourse/templates/user/username.js.handlebars

@@ -23,9 +23,7 @@
       {{#if controller.taken}}
         {{i18n user.change_username.taken}}
       {{/if}}
-      {{#if controller.invalid}}
-        {{i18n user.change_username.invalid}}
-      {{/if}}
+      <span>{{ errorMessage }}</span>
     </div>
   </div>