Fatal error: Uncaught Error: Call to undefined function Heartbeat_Control\apply_filters() in /home/spirqnft/setmyflight.com/wp-content/plugins/heartbeat-control/heartbeat-control.php:74 Stack trace: #0 /home/spirqnft/setmyflight.com/wp-content/plugins/heartbeat-control/heartbeat-control.php(34): Heartbeat_Control\Heartbeat_Control->maybe_upgrade() #1 /home/spirqnft/setmyflight.com/wp-content/plugins/heartbeat-control/heartbeat-control.php(153): Heartbeat_Control\Heartbeat_Control->__construct() #2 {main} thrown in /home/spirqnft/setmyflight.com/wp-content/plugins/heartbeat-control/heartbeat-control.php on line 74