Error when trying to register

Warning: Creating default object from empty value in /home/bulewold7/public_html/web/clearcharity-org/wp-includes/capabilities.php on line 655

Warning: Cannot modify header information – headers already sent by (output started at /home/bulewold7/public_html/web/clearcharity-org/wp-includes/capabilities.php:655) in /home/bulewold7/public_html/web/clearcharity-org/wp-includes/pluggable.php on line 1121

I get these error when I try to register using this form. I do have woocommerce and WP Symposium installed. Can anyone help?

https://wordpress.org/plugins/theme-my-login/