Drupal.settings.beautytips[key].list is undefined

When not adding other options then area and text to the beautytips_add_beautytips() function there is an javascript error in beautytips.js at line 19

Drupal.settings.beautytips[key].list is undefined
[Break on this error] for ( var k = 0; k < Drupal.setti....beautytips[key]['list'].length; k++) {\n

Looking at the beautytips.module (line 148) that this variable only is set if there are other options than area and text. The manual of the API function describes that area and text are only needed, and that all other options are optional. But this seems not to be the case.