added env path for cover to Song entity

src/Entity/Song.php

@@ -573,7 +573,8 @@ class Song
             'uploadDate' => $this->uploadDate,
             'updateDate' => $this->updateDate,
             'updateHash' => $this->updateHash,
-            'description' => $this->description
+            'description' => $this->description,
+            'cover' => $_ENV['ASSET_BASE_URL'].DIRECTORY_SEPARATOR.$_ENV['ASSET_COVER_FOLDER'].DIRECTORY_SEPARATOR.$this->getFileReference().".png"
         );
     }