The result of configureLists is immediately used in a foreach() in a couple of places without checking it's an array. This causes warnings like
Warning: Invalid argument supplied for foreach() in CRM_Mailchimp_Utils::checkGroupsConfig() (line 228 of uk.co.vedaconsulting.mailchimp/CRM/Mailchimp/Utils.php).
The result of configureLists is immediately used in a foreach() in a couple of places without checking it's an array. This causes warnings like