Error Messages

In the dashboard at the top, getting the following message upon activation. Is there issues with cache and this plugin? We are hosted on SiteGround.

Warning: Invalid argument supplied for foreach() in /home/enter869/citynet/wp-content/plugins/heartbeat-control/heartbeat-control.php on line 129

Warning: Cannot modify header information – headers already sent by (output started at /home/enter869/citynet/wp-content/plugins/heartbeat-control/heartbeat-control.php:129) in /home/enter869/citynet/wp-includes/functions.php on line 6221