$submission = $this->get_submission($userid);
- if ($files = $fs->get_area_files($this->context->id, 'mod_assignment', 'submission', $submission->id, "timemodified", false)) {
+ if (($submission) && $files = $fs->get_area_files($this->context->id, 'mod_assignment', 'submission', $submission->id, "timemodified", false)) {
require_once($CFG->libdir.'/portfoliolib.php');
require_once($CFG->dirroot . '/mod/assignment/locallib.php');
$button = new portfolio_add_button();