refactor: code

lib/Server.js

@@ -447,10 +447,6 @@ class Server {
     const compilerWatchOptions = compilerOptions.watchOptions || {};
 
     const getDefaultWatchOptions = (watchOptions = {}) => {
-      watchOptions = {
-        ...compilerWatchOptions,
-        ...watchOptions,
-      };
       // duplicate the same massaging of options that watchpack performs
       // https://github.com/webpack/watchpack/blob/master/lib/DirectoryWatcher.js#L49
       // this isn't an elegant solution, but we'll improve it in the future
@@ -468,17 +464,14 @@ class Server {
           : // eslint-disable-next-line no-undefined
             undefined;
 
-      if (watchOptions.poll) {
-        delete watchOptions.poll;
-      }
-
-      const finalWatchOptions = {
+      const { poll, ...finalWatchOptions } = {
         ignoreInitial: true,
         persistent: true,
         followSymlinks: false,
         atomic: false,
         alwaysStat: true,
         ignorePermissionErrors: true,
+        ...compilerWatchOptions,
         ...watchOptions,
         ignored: watchOptions.ignored,
         usePolling,