TypeError when sending Email Marketer Rules
After updating to WHMCS 8.6.1, you may see a
TypeError error when sending Email Marketer rules during the automation tasks:
TypeError: array_search(): Argument #2 ($haystack) must be of type array, null given in /path/to/whmcs/vendor/whmcs/whmcs-foundation/lib/Cron/Task/EmailMarketer.php:0
An invalid value in the Email Marketer rule (missing billing cycle) causes an error in PHP 8.1 environments only.