Undefined index: cache_list in performance_apc_list_all

Running cron, I get the following message(s):

* Notice: Undefined index: cache_list in performance_apc_list_all() (regel 405 van devel\performance\performance.module).
* Warning: Invalid argument supplied for foreach() in performance_apc_list_all() (regel 405 van devel\performance\performance.module).

On my system the return value of apc_cache_info('user') is an empty array. Surrounding the foreach with an
if (!empty($list['cache_list'])) {
}
prevents the warning from being shown.