Using the Joomla Latest Events module I received the following error message:
Warning: array_key_exists(): The second argument should be either an array or an object in /path/to/website/modules/mod_events_latest.lib.php on line 241
Solved by adding the following line:
var $eventsByDay = array();
after:
class JEventsLatest {
in the file:
/path/to/website/modules/mod_events_latest.lib.php
