Issue #592: Handle missing gradeitems as gracefully as possible

element/gradeitemname/classes/element.php

@@ -121,7 +121,9 @@ protected function get_grade_item_name() : string {
             $gradeitemid = substr($gradeitem, 10);
             $gradeitem = \grade_item::fetch(['id' => $gradeitemid]);
 
-            return $gradeitem->get_name();
+            // If the gradeitem was not found, return an empty string.
+            // This will effectively prevent the element from rendering.
+            return $gradeitem ? $gradeitem->get_name() : '';
         } else {
             if (!$cm = $DB->get_record('course_modules', array('id' => $gradeitem))) {
                 return '';
@@ -141,7 +143,9 @@ protected function get_grade_item_name() : string {
 
             $gradeitem = \grade_item::fetch($params);
 
-            return $gradeitem->get_name();
+            // If the gradeitem was not found, return an empty string.
+            // This will effectively prevent the element from rendering.
+            return $gradeitem ? $gradeitem->get_name() : '';
         }
     }
 }