handle empty variety sessions

booking.variety_admin.inc

@@ -553,6 +553,13 @@ function booking_varietysessions_csv_report($timeslot_id) {
     array(':eid' => $event->eid));
   $session_members = $session_members_query->fetchAll();
 
+  // Check if we had no data added, that means there were no people in this study group
+  if (! $session_members) {
+    drupal_set_message("Error: Variety Session timeslot $timeslot_id has no members assigned.", 'error', FALSE);
+		drupal_goto('admin/booking/variety');    
+		return "";
+  }    
+  
   //watchdog('booking_debug', 'booking_varietysessions_csv_report session members: <pre>@info</pre>', array('@info' => print_r( $session_members, true)));
   
   //generate the row data