MDL-41996: Don't show the Review Attempt link if no attempts exist.

mod/quiz/report/attemptsreport_table.php

@@ -138,7 +138,7 @@ public function col_picture($attempt) {
      */
     public function col_fullname($attempt) {
         $html = parent::col_fullname($attempt);
-        if ($this->is_downloading()) {
+        if ($this->is_downloading() || empty($attempt->attempt)) {
             return $html;
         }