Plugin update failed

I have just tried to update the plugin and I get the following error
Create, print & email PDF invoices & packing slips for WooCommerce orders.

Version 2.3.5 | By Ewout Fernhout | View details
This plugin failed to load properly and is paused during recovery mode.

An error of type E_ERROR was caused in line 751 of the file /home/plyt5905/public_html/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/documents/abstract-wcpdf-order-document.php. Error message: Uncaught Error: Call to a member function mailer() on null in /home/plyt5905/public_html/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/documents/abstract-wcpdf-order-document.php:751 Stack trace: #0 /home/plyt5905/public_html/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/documents/class-wcpdf-invoice.php(181): WPO\WC\PDF_Invoices\Documents\Order_Document->get_wc_emails() #1 /home/plyt5905/public_html/wp-content/plugins/woocommerce-pdf-invoices-packing-slips/includes/class-wcpdf-settings-documents.php(20): WPO\WC\PDF_Invoices\Documents\Invoice->init_settings() #2 /home/plyt5905/public_html/wp-includes/class-wp-hook.php(286): WPO\WC\PDF_Invoices\Settings_Documents->init_settings(”) #3 /home/plyt5905/public_html/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array) #4 /home/plyt5905/public_html/wp-includes/plugin.php(465): WP_Hook->do_action(Array) #5 /home/plyt5905/public_html/wp-admin/admin.php(169): do_action(‘admin_init’) #6 /home/plyt5905/public_h