The best time to register for DrupalCon Dublin is now. Earlybird discounts end July 29.
The error is
Notice: Undefined property: stdClass::$taxonomy_title in taxonomy_title_taxonomy_term_insert() (line 65 of ...taxonomy_title/taxonomy_title.module).
Checking if the term title is set before inserts (and updates) will prevent this from firing where the values are not set.
Oh. it looks like this is a duplicate of #1236838: Error when adding tags to an article
Moving patch over there.
Drupal is a registered trademark of Dries Buytaert.