HEAD requests have no body, only HTTP response code, so we need to act accordingly

goes.go

@@ -345,10 +345,14 @@ func (req *Request) Run() (Response, error) {
 	}
 
 	esResp := new(Response)
+    if req.method == "HEAD" {
+        esResp.Status = uint64(resp.StatusCode)
+    } else {
         err = json.Unmarshal(body, &esResp)
         if err != nil {
             return Response{}, err
         }
+    }
 
 	if req.api == "_bulk" && esResp.Errors {
 		for _, item := range esResp.Items {