fs: use w flag for writeFileSync when flag not specified

Author: MuriloKakazu

lib/fs.js

@@ -2343,6 +2343,8 @@ function writeFileSync(path, data, options) {
 
   validateBoolean(flush, 'options.flush');
 
+  const flag = options.flag || 'w';
+
   // C++ fast path for string data and UTF8 encoding
   if (typeof data === 'string' && (options.encoding === 'utf8' || options.encoding === 'utf-8')) {
     if (!isInt32(path)) {
@@ -2351,7 +2353,7 @@ function writeFileSync(path, data, options) {
 
     return binding.writeFileUtf8(
       path, data,
-      stringToFlags(options.flag),
+      stringToFlags(flag),
       parseFileMode(options.mode, 'mode', 0o666),
     );
   }
@@ -2361,8 +2363,6 @@ function writeFileSync(path, data, options) {
     data = Buffer.from(data, options.encoding || 'utf8');
   }
 
-  const flag = options.flag || 'w';
-
   const isUserFd = isFd(path); // File descriptor ownership
   const fd = isUserFd ? path : fs.openSync(path, flag, options.mode);