Can't download invoice

Will get following errorcode:

Warning : chr() expects parameter 1 to be int, string given in /srv/users/wordpress/apps/wordpress/public/wp-content/plugins/edd-pdf-invoices/tcpdf/tcpdf.php on line 7773

Warning : Cannot modify header information - headers already sent by (output started at /srv/users/wordpress/apps/wordpress/public/wp-content/plugins/edd-pdf-invoices/tcpdf/tcpdf.php:7773) in /srv/users/wordpress/apps/wordpress/public/wp-content/plugins/edd-pdf-invoices/tcpdf/tcpdf.php on line 9064
TCPDF ERROR: Some data has already been output to browser, can’t send PDF file

Pls fix. Need the invoice. Ty!

This is most likely an error in the third party plugin the web store uses. I can make a note to take a look but since I am not a web developer and my time is very limited, we may have to wait until the developer of the plugin fixes the issue.