"Undefined index" error with d6-d7 migrate

If this module is installed on a Drupal 7 site and I use the migrate module to import from a Drupal 6 site (which does not have this module installed), I get a lot of error messages like this:

Undefined index: image_field_caption File /path/to/public_html/sites/all/modules/contrib/image_field_caption/image_field_caption.module, line 221 (file: /path/to/public_html/sites/all/modules/contrib/image_field_caption/image_field_caption.module, line 221)

I don't know if the attached patch is the best approach, but it solved the problem for me. It checks whether $item['image_field_caption'] is set on the incoming node before trying to do the insert. It also fixes a misspelling in a comment.