Cannot register additional volunteers

When registering a volunteer plus "Additional Volunteers" (any quantity) an error is encountered after filling out all the appropriate information and clicking Submit:

Recoverable fatal error: Argument 2 passed to CRM_Volunteer_Form_VolunteerSignUp::createVolunteerActivity() must be of the type array, none given, called in /var/www/civivolunteer.ginkgostreet.com/htdocs/sites/default/ext/org.civicrm.volunteer/CRM/Volunteer/Form/VolunteerSignUp.php on line 392 and defined in CRM_Volunteer_Form_VolunteerSignUp->createVolunteerActivity() (line 452 of /var/www/civivolunteer.ginkgostreet.com/htdocs/sites/default/ext/org.civicrm.volunteer/CRM/Volunteer/Form/VolunteerSignUp.php).

Have tried multiple profiles with the same results. Replicated on http://civivolunteer.ginkgostreet.com/.

Some portion of the registration actually does work but the expected behavior of each of the volunteers being assigned to the appropriate shift as individual contact records does not happen. In some cases, one contact record is assinged to the same shift more than once (if one email address is used) and if multiple emails are used, only one is assigned to the shift.