500 error occurs when placing an order, how to avoid?

Question

WordPress

Good afternoon, I use the hook - woocommerce_email_after_order_table, in order to do a little integration with the crm system, there is a small self-written class crm.php
before executing the hook, I connect this class

include('crm/crm.php');
add_action( 'woocommerce_email_after_order_table', 'custom_email_after_order_table', 99, 4 );
function custom_email_after_order_table( $order, $sent_to_admin, $plain_text, $email ) {
  $crm = new crm();
}

the class is connected correctly was checked on another hook, but when executing a piece of code , a 500 error occurs, what's the catch?
$crm = new crm();