FIX: Groups post page was broken.

Also added integration tests so we don't miss this breaking in the
future.

app/assets/javascripts/discourse/helpers/category-link.js.es6

@@ -32,7 +32,7 @@ export function categoryBadgeHTML(category, opts) {
 
   var html = "";
 
-  var parentCat = Discourse.Category.findById(category.get('parent_category_id'));
+  var parentCat = Discourse.Category.findById(get(category, 'parent_category_id'));
   if (opts.hideParent) { parentCat = null; }
   html += categoryStripe(tagName, parentCat, extraClasses, href);
 

app/assets/javascripts/discourse/templates/group/members.hbs

@@ -4,7 +4,7 @@
       <th colspan="3" class="seen">{{i18n 'last_seen'}}</th>
     </tr>
   {{#each m in members}}
-  <tr>
+    <tr>
       <td class='avatar'>
         {{avatar m imageSize="large"}}
       </td>
@@ -16,7 +16,6 @@
         <span class='last-seen-at'>{{bound-date m.last_seen_at}}</span>
       </td>
     </tr>
-    </div>
   {{/each}}
 </table>
 {{/if}}