remove php warning from report page when no sessions exist

diff --git a/renderer.php b/renderer.php
index 6b7cdbf..cbfa0ab 100755 (executable)
--- a/renderer.php
+++ b/renderer.php
@@ -816,7 +816,7 @@ class mod_attendance_renderer extends plugin_renderer_base {
             }
 
             if ($reportdata->sessionslog) {
-                if (isset($reportdata->sessionslog[$user->id][$sess->id]->remarks)) {
+                if (isset($sess) && isset($reportdata->sessionslog[$user->id][$sess->id]->remarks)) {
                     $row->cells[] = $reportdata->sessionslog[$user->id][$sess->id]->remarks;
                 } else {
                     $row->cells[] = '';