[Timeline] Fixed if no QSOs found.

application/models/Timeline_model.php

@@ -8,6 +8,10 @@ class Timeline_model extends CI_Model
 		$CI->load->model('logbooks_model');
 		$logbooks_locations_array = $CI->logbooks_model->list_logbook_relationships($this->session->userdata('active_station_logbook'));
 
+        if (!$logbooks_locations_array) {
+            return null;
+        }
+
 		$location_list = "'".implode("','",$logbooks_locations_array)."'";
 
         switch ($award) {