Improve invoice period data and POS add-on validation

services/nginx/app/classes/pdf_store.php

@@ -62,7 +62,7 @@ class pdf_store implements minio_pdfs_i
 
     public function isFileInStore(string $file): bool
     {
-        return self::getS3Client()->doesObjectExist(self::getBucket(), $file);
+        return self::doesObjectExist($file);
     }
 
     /**
@@ -76,4 +76,4 @@ class pdf_store implements minio_pdfs_i
             $file_path
         );
     }
-}
+}