displays a message when a failure happen while creating a new category

app/assets/javascripts/discourse/templates/modal/edit_category.js.handlebars

@@ -1,7 +1,7 @@
-<div class="modal-body">    
+<div class="modal-body">
   <form>
     <label>{{i18n category.name}}</label>
-    {{view Discourse.TextField valueBinding="view.category.name" placeholderKey="category.name_placeholder"}}
+    {{view Discourse.TextField valueBinding="view.category.name" placeholderKey="category.name_placeholder" maxlength="50"}}
 
     <div class='description-controls' style="margin-bottom: 20px">
       <label>{{i18n category.description}}</label>
@@ -12,7 +12,7 @@
           <a href="#" {{action showCategoryTopic target="view"}}>{{i18n category.change_in_category_topic}}</a>
         {{/if}}
       {{else}}
-        {{i18n category.no_description}} 
+        {{i18n category.no_description}}
           {{#if view.category.topic_url}}
           <a {{action showCategoryTopic target="view"}} href="#">{{i18n category.change_in_category_topic}}</a>
           {{/if}}}
@@ -31,4 +31,4 @@
 </div>
 <div class="modal-footer">
   <button class='btn btn-primary' {{bindAttr disabled="view.disabled"}} {{action saveCategory target="view"}}>{{view.buttonTitle}}</button>
-</div>  
+</div>

app/assets/javascripts/discourse/views/modal/edit_category_view.js

@@ -59,7 +59,12 @@ Discourse.EditCategoryView = Discourse.ModalBodyView.extend({
         _this.saveSuccess(result);
       },
       error: function(errors) {
+        // displays a generic error message when none is sent from the server
+        // this might happen when some "after" callbacks throws an exception server-side
+        if(errors.length === 0) errors.push(Em.String.i18n("category.creation_error"));
+        // display the errors
         _this.displayErrors(errors);
+        // not saving anymore
         _this.set('saving', false);
       }
     });