perf: avoid useless Object.entries (#167)

* perf: avoid useless Object.entry

* style: fix lint

* Skip the headers loop also when headers is null

Author: nigrosimone

index.js

@@ -259,8 +259,10 @@ function send (req, res, status, headers, message) {
     res.removeHeader('Content-Range')
 
     // response headers
-    for (const [key, value] of Object.entries(headers ?? {})) {
-      res.setHeader(key, value)
+    if (headers) {
+      for (const [key, value] of Object.entries(headers)) {
+        res.setHeader(key, value)
+      }
     }
 
     // security headers