Avoid exception on empty link href/title

src/RemoteMenuParser.php

@@ -11,6 +11,7 @@ use Drupal\Core\Cache\RefinableCacheableDependencyInterface;
 use Drupal\Core\Config\Config;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Menu\MenuLinkTreeElement;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
 use GuzzleHttp\Client;
 
 /**
@@ -18,6 +19,8 @@ use GuzzleHttp\Client;
  */
 class RemoteMenuParser {
 
+  use StringTranslationTrait;
+
   /**
    * The HTTP client.
    *
@@ -97,7 +100,9 @@ class RemoteMenuParser {
     // Convert a flat JSON into a tree array.
     foreach ($json_parsed->linkset[0]->item as $item) {
       $location = static::parseLocation($item);
-      $data = static::insertLink($location, $item->href, $item->title, $data);
+      $link_href = $item->href ?? '';
+      $link_title = $item->title ?? (string) $this->t('- Missing Link Title -');
+      $data = static::insertLink($location, $link_href, $link_title, $data);
     }
     // Convert the tree array into a tree of RemoteMenuLink objects.
     $base_url = parse_url($url, PHP_URL_SCHEME) . '://' . parse_url($url, PHP_URL_HOST);