fix to avoid querying for Shifts when none were found in the list of hours.  This fixed the apex runtime error exception 'GW_Volunteers__Volunteer_Shift__C is not supported when querying for the shifts, which seemed to only get hit on some Users with more limited permissions.
fix to avoid querying for Shifts when none were found in the list of hours.  This fixed the apex runtime error exception 'GW_Volunteers__Volunteer_Shift__C is not supported when querying for the shifts, which seemed to only get hit on some Users with more limited permissions.

SalesforceFoundation/Volunteers-for-Salesforce