fix context call and debug messages from remarks code

locallib.php

@@ -895,7 +895,7 @@ class attendance {
             }
         }
 
-        $totalusers = count_enrolled_users(get_context_instance(CONTEXT_MODULE, $this->cm->id), 'mod/attendance:canbelisted', $group);
+        $totalusers = count_enrolled_users(context_module::instance($this->cm->id), 'mod/attendance:canbelisted', $group);
         $usersperpage = $this->pageparams->perpage;
 
         if (!empty($this->pageparams->page) && $this->pageparams->page && $totalusers && $usersperpage) {

renderer.php

@@ -803,7 +803,11 @@ class mod_attendance_renderer extends plugin_renderer_base {
             }
 
             if ($reportdata->sessionslog) {
-                $row->cells[] = $reportdata->sessionslog[$user->id][$sess->id]->remarks;
+                if (isset($reportdata->sessionslog[$user->id][$sess->id]->remarks)) {
+                    $row->cells[] = $reportdata->sessionslog[$user->id][$sess->id]->remarks;
+                } else {
+                    $row->cells[] = '';
+                }
             }
             $table->data[] = $row;
         }