Tems Management and Thesis

I have been having problems with the terms management plugin from scribu. When I merge terms, I get:

Warning: Missing argument 2 for thesis_term_options::delete_term() in /home/eldergat/public_html/articles/wp-content/themes/thesis/lib/classes/options_terms.php on line 173

Warning: Cannot modify header information – headers already sent by (output started at /home/eldergat/public_html/articles/wp-content/themes/thesis/lib/classes/options_terms.php:173) in /home/eldergat/public_html/articles/wp-includes/pluggable.php on line 897

I am using Thesis 1.8. Once I get the error message, I back page and do the action again and it goes through successfully. Weird, huh.

Deleting terms usual produces an error message but the term is deleted.

Any suggestions would be appreciated.