PHP warning: Use of undefined constant purchaser_name & others – PHP Versions

Good morning,

I’m unfamiliar with debugging and diagnosing PHP issues (surface-level knowledge at best). I have a client who, from a previous developer, has some custom functions setup in their theme’s functions.php file. One of these functions send an event certificate once a certain product has been purchased to the attendees of said event.

Recently, after upgrading our child theme and running through a few other updates, we’re getting a PHP warning displayed on this page. The emails still send out as expected, however I wanted to check in on this warning before it potentially became a bigger issue.

The warnings are as follows:

Warning: Use of undefined constant purchaser_name – assumed
‘purchaser_name’ (this will throw an Error in a future version of PHP)
in
/public_html/wp-content/themes/hr-advisor-child/functions.php
on line 293

Warning: Use of undefined
constant purchaser_email – assumed ‘purchaser_email’ (this will throw
an Error in a future version of PHP) in
/public_html/wp-content/themes/hr-advisor-child/functions.php
on line 294

Warning: Use of undefined
constant ticket_name – assumed ‘ticket_name’ (this will throw an Error
in a future version of PHP) in
/public_html/wp-content/themes/hr-advisor-child/functions.php
on line 295

Warning: count(): Parameter
must be an array or an object that implements Countable in
/public_html/wp-content/plugins/wp-mail-log/classes/capture-mail.php
on line 23
-> Sent to Jordan Lovelle<redacted]>.

The code for this function is as follows:

function send_certificate($request)
{
    $event_id = $request['event_id'];
    $event_name = urlencode(get_the_title($event_id));
    $event_date = tribe_get_start_date($event_id, false, 'jS F Y');
    
    $wootickets = Tribe__Tickets_Plus__Commerce__WooCommerce__Main::get_instance();
    $attendees = $wootickets->get_attendees_by_id( $event_id );
    
    echo "Sending certificate. rn";
    echo "============================rnrn";
    
    foreach ( (array) $attendees as $attendee ) {
        if ( $attendee['check_in'] == 1 ) {

            $attendee_name = $attendee[purchaser_name];
            $attendee_email = $attendee[purchaser_email];
            $event_subtitle = $attendee[ticket_name];
            
            $dataArray = array(
                "name"=>$attendee_name, 
                "event_name"=>$event_name, 
            );
           
            $url = "https://<redacted>/wp-content/themes/hr-advisor-child/certificate/getPDF.php?" . http_build_query($dataArray, '', '&', PHP_QUERY_RFC3986);
            error_log($url);
            
            $certificate = url_get_contents($url);
            file_put_contents(get_stylesheet_directory() . "/certificate/certificate.pdf", $certificate);
            
            $to = $attendee_email;
            $subject = "Here's your certificate from the event";
            $headers[] = 'From: <redacted> <no-reply@<redacted>>';
            $headers[] = 'Content-Type: text/html; charset=UTF-8';
            $message = file_get_contents(get_stylesheet_directory() . "/certificate/email.php");
            wp_mail( $to, $subject, $message, $headers, get_stylesheet_directory() . "/certificate/certificate.pdf" );
            
            
            echo "    -> Sent to $attendee_name<$attendee_email>.rn";
        }
    }
    
    echo "rnrn============================rn";
    echo "All done. rn";
    exit();
}

Any help to understand why these warnings occur and how to fix it would be very much appreciated.

Thanks,
Jordan.