A PHP Error was encountered

Severity: Notice

Message: Undefined index: topics-city-shopping

Filename: controllers/Content.php

Line Number: 664

Backtrace:

File: /home/flashcardo/webapps/flashcardo/application/controllers/Content.php
Line: 664
Function: _error_handler

File: /home/flashcardo/webapps/flashcardo/public/index.php
Line: 315
Function: require_once