http: delay ret declaration in method _flushOutput

PR-URL: nodejs#26562
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/_http_outgoing.js

@@ -791,13 +791,13 @@ OutgoingMessage.prototype._flush = function _flush() {
 };
 
 OutgoingMessage.prototype._flushOutput = function _flushOutput(socket) {
-  var ret;
-  var outputLength = this.outputData.length;
+  const outputLength = this.outputData.length;
   if (outputLength <= 0)
-    return ret;
+    return undefined;
 
-  var outputData = this.outputData;
+  const outputData = this.outputData;
   socket.cork();
+  let ret;
   for (var i = 0; i < outputLength; i++) {
     const { data, encoding, callback } = outputData[i];
     ret = socket.write(data, encoding, callback);