diff --git a/core/lib/Drupal/Core/Menu/MenuLinkDefault.php b/core/lib/Drupal/Core/Menu/MenuLinkDefault.php
index f4ff911..c17fe79 100644
--- a/core/lib/Drupal/Core/Menu/MenuLinkDefault.php
+++ b/core/lib/Drupal/Core/Menu/MenuLinkDefault.php
@@ -74,10 +74,7 @@ public function getTitle() {
    * {@inheritdoc}
    */
   public function getDescription() {
-    if ($this->pluginDefinition['description']) {
-      return (string) $this->pluginDefinition['description'];
-    }
-    return '';
+    return (string) $this->pluginDefinition['description'];
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Menu/MenuTreeStorage.php b/core/lib/Drupal/Core/Menu/MenuTreeStorage.php
index b33dacc..11e3711 100644
--- a/core/lib/Drupal/Core/Menu/MenuTreeStorage.php
+++ b/core/lib/Drupal/Core/Menu/MenuTreeStorage.php
@@ -365,7 +365,9 @@ protected function preSave(array &$link, array $original) {
     $fields['route_param_key'] = $fields['route_parameters'] ? UrlHelper::buildQuery($fields['route_parameters']) : '';
 
     foreach ($this->serializedFields() as $name) {
-      $fields[$name] = serialize($fields[$name]);
+      if (isset($fields[$name])) {
+        $fields[$name] = serialize($fields[$name]);
+      }
     }
     $this->setParents($fields, $parent, $original);
 
@@ -617,7 +619,9 @@ protected function updateParentalStatus(array $link) {
    */
   protected function prepareLink(array $link, $intersect = FALSE) {
     foreach ($this->serializedFields() as $name) {
-      $link[$name] = unserialize($link[$name]);
+      if (isset($link[$name])) {
+        $link[$name] = unserialize($link[$name]);
+      }
     }
     if ($intersect) {
       $link = array_intersect_key($link, array_flip($this->definitionFields()));
@@ -734,7 +738,9 @@ protected function loadFullMultiple(array $ids) {
     $loaded = $this->safeExecuteSelect($query)->fetchAllAssoc('id', \PDO::FETCH_ASSOC);
     foreach ($loaded as &$link) {
       foreach ($this->serializedFields() as $name) {
-        $link[$name] = unserialize($link[$name]);
+        if (isset($link[$name])) {
+          $link[$name] = unserialize($link[$name]);
+        }
       }
     }
     return $loaded;