Fixes: #639 when there is no argonaut server we got an error in the log

include/jsonRPCClient.php

@@ -130,7 +130,7 @@ class jsonRPCClient {
               'content' => $request
               ));
     $context  = stream_context_create($opts);
-    if ($fp = fopen($this->url, 'r', false, $context)) {
+    if ($fp = @fopen($this->url, 'r', false, $context)) {
       $response = '';
       while($row = fgets($fp)) {
         $response.= trim($row)."\n";