Adding a transition causes error

Drupal CVS, php 4.3.8, OS X, MySQL 4.0.12-standard.

Whenever I add a transition, I get these errors:

warning: array_key_exists(): The second argument should be either an array or an object in /Library/WebServer/Documents/drupal/modules/workflow/workflow.module on line 874.

warning: Cannot modify header information - headers already sent by (output started at /Library/WebServer/Documents/drupal/includes/common.inc:346) in /Library/WebServer/Documents/drupal/includes/common.inc on line 156.

and I'm not redirected to the workflow page. Going back into edit mode to see if the transition was added shows it was, though, so I have no idea why these annoying errors pop-up.