‘Add fee’ breaks website

I have added the below code so I would be able to use the product title in the email templates

//Custom email format
add_filter( 'woocommerce_email_format_string' , 'add_custom_email_format_string', 10, 2 );
function add_custom_email_format_string( $string, $email ) {
    $order       = $email->object; // Get the instance of the WC_Order OBJECT
    $order_items = $order->get_items(); // Get Order items
    $order_item  = reset($order_items); // Get the irst order item

    $string = str_replace( '{subscription_name}', $order_item->get_name(), $string );

    return $string; 
}

However, if I add an order manually and add a fee instead of a product, and try to send the customer invoice / order details email to the customer to pay, my website throws an error that it has run into a critical error and points this line of code to be the issue:

$string = str_replace( '{subscription_name}', $order_item->get_name(), $string );

The exact error is:

Error Details
=============
An error of type E_ERROR was caused in line 573 of the file
/wp-content/themes/Divi-child/functions.php.
Error message: Uncaught Error: Call to a member function get_name() on
bool in /public_html/quest/wp-content/themes/Divi-child/functions.php:573
Stack trace:
#0 /public_html/quest/wp-includes/class-wp-hook.php(287):
add_custom_email_format_string('Your latest QUE...',
Object(WC_Email_Customer_Invoice))
#1 /public_html/quest/wp-includes/plugin.php(206):
WP_Hook->apply_filters('Your latest QUE...', Array)
#2 /public_html/quest/wp-content/plugins/woocommerce/includes/emails/class-wc-email.php(310):
apply_filters('woocommerce_ema...', 'Your latest QUE...',
Object(WC_Email_Customer_Invoice))
#3 /public_html/quest/wp-content/plugins/woocommerce/includes/emails/class-wc-email-customer-invoice.php(90):
WC_Email->format_string('Your latest {si...')
#4 /public_html/quest/wp-content/plugins/woocommerce/includes/emails/class-wc-email-customer-invoice.php(139):
WC_Email_Customer_Invoice->get_subject()
#5 /public_html/quest/wp-content

How can I modify this so I can still use the product name in some of the emails but still be able to add custom fees when needed? I need to use the ‘add fee’ option to send custom payment amounts to clients for grandfathered subscriptions.

• This topic was modified 5 years, 10 months ago by businesscloudinc. Reason: added error details