user_shifts fixed error with empty shifts table

includes/pages/user_shifts.php

@@ -103,6 +103,8 @@ function user_shifts() {
 	} else {
 		$shifts = sql_select("SELECT * FROM `Shifts` ORDER BY `start`");
 		$days = array ();
+		$rooms = array ();
+		if (count($shifts) > 0) {
 			foreach ($shifts as $shift)
 				$days[] = date("Y-m-d", $shift['start']);
 			$days = array_unique($days);
@@ -159,6 +161,7 @@ function user_shifts() {
 				if ($id != 0 || ($show_shift && $row_count++ < 15))
 					$shifts_table .= $shift_row . '</td></tr>';
 			}
+		}
 
 		return template_render('../templates/user_shifts.html', array (
 			'room_select' => make_room_select($rooms, $id, $day),