Fatal error: Unsupported operand types in \sites\all\modules\votingapi\votingapi.module on line 476

Description

Once a fivestar CCK field has been added to any node type, any new nodes (or edits to existing nodes) result in the following error PHP error message being displayed upon clicking the 'submit' buttons:

Fatal error: Unsupported operand types in \sites\all\modules\votingapi\votingapi.module on line 476
Steps to reproduce:

* Activate the Fivestar module
* Add a new node type
* Add a new fivestar rating field (star or radio, doesn't seem to matter)
* Whether clearing is allowed, whether required or optional, and number of stars don't seem to matter
* Create a new node of that type and try to set a rating
* Click submit

Other background information:
Drupal version 6.12
Voting api version: 6.x-2.0-RC2
Fivestar 6.x-1.15