generate keywords on file parsed only

src/Service/TorrentService.php

@@ -154,8 +154,8 @@ class TorrentService
     {
         $keywords = [];
 
-        $file = $this->readTorrentFileByFilepath($filepath);
-
+        if ($file = $this->readTorrentFileByFilepath($filepath))
+        {
             foreach ($file->getFileList() as $file)
             {
                 $words = explode(
@@ -196,6 +196,7 @@ class TorrentService
 
                 $keywords = array_merge($keywords, $words);
             }
+        }
 
         return array_unique($keywords);
     }