Ajax parser issues with Common.inc after running php script via rules

I get this pop up after running a rule:

An AJAX HTTP error occurred.
HTTP Result Code: 200
Debugging information follows.
Path: /~dacapo5/rc/system/ajax
StatusText: parsererror
ResponseText:
Fatal error: Class name must be a valid object or a string in /home/dacapo5/public_html/rc/includes/common.inc on line 7837

Rule:
Event - User clicks a button field
Conditions: Entity is of type: Registration (Entity Registration)
Actions: Execute Custom PHP Code

Custom PHP Code -

The code gets values from the registration and the entity that created the registration (Event Calendar Content type).
It will then create a JSON file and sign it to create an Apple Passbook PKPass object
It will create an HTML email with attachments (PKpass obhect) and send it out to the user.

The line in common.inc is the following:

function entity_get_controller($entity_type) {
$controllers = &drupal_static(__FUNCTION__, array());
if (!isset($controllers[$entity_type])) {
$type_info = entity_get_info($entity_type);
$class = $type_info['controller class'];
$controllers[$entity_type] = new $class($entity_type);
}
return $controllers[$entity_type];
}
Note, the PHP code has no reference to common.inc directly its interface with drupal is as follow:

require('sites/all/libraries/QRUPass/src/PKPass/PKPass.php');
// rcbd demo event ticket

$fname = $registration->field_first_name[0][0]['value'];
$lname = $registration->field_surname[0][0]['value'];
$emailto = $registration->field_registration_email[0][0]['value'];
$fullname = $fname.''.$lname;
$din = $registration->field_din[0][0]['value'];
$photoid = $registration->field_photoid[0][0]['uri'];
$event_type = $registration->type;
$event = entity_load_single($registration->entity_type, $registration->entity_id);
if (empty($event)) {
echo "severe error cannot get event :".$registration->entity_id."type = ".$registration->entity_type;
return false;
}
$event_title = $event->title;
$event_image = $event->field_image[0][0]['uri'];
$event_from = $event->field_date[0][0]['value'];
$event_to = $event->field_date[0][0]['value2'];
$event_organizer = $event->field_event_organizer[0][0]['value'];
$event_contact_number = $event->field_event_contact_number[0][0]['value'];
$event_rc_chapter = $event->field_red_cross_chapter[0][0]['value'];
$event_location = $event->field_event_location[0][0]['name'];
$event_street = $event->field_event_location[0][0]['street'];
$event_street2 = $event->field_event_location[0][0]['additional'];
$event_city = $event->field_event_location[0][0]['city'];
$event_province = $event->field_event_location[0][0]['province'];
$event_country = $event->field_event_location[0][0]['country'];
$event_address = $event_location.",\n".$event_street;
if (!empty($event_street2)) {
$event_address .= "\n".$event_street2;
}
$event_address = ",\n".$event_city;
if (!empty($event_province)) {
$event_address .= ", ".$event_province;
}
$serialnumber = $din;
$pass = new PKPass\PKPass();