fixed some issues

Author: jxd23

public/src/client/register.js

@@ -131,7 +131,7 @@ define('forum/register', [
                 if (results.every(obj => obj.status === 'rejected')) {
                     showSuccess(username_notify, successIcon);
                 } else {
-                    showError(username_notify, '[[error:username-taken, ${username}]]');
+                    showError(username_notify, `[[error:username-taken, ${username}]]`);
                 }
 
                 callback();