Fix webpack dev server freezing after repeated refreshes (#9865)

webpack.config.js

@@ -36,6 +36,15 @@ module.exports = async function (env, argv) {
   ]
   if (env.mode === 'development') {
     config.plugins.push(new ReactRefreshWebpackPlugin())
+    // Reap zombie HMR WebSocket connections that linger after refresh.
+    // Without this, dead sockets exhaust the browser's per-origin connection
+    // pool and the dev server stops responding.
+    config.devServer.onListening = devServer => {
+      devServer.server.on('connection', socket => {
+        socket.setTimeout(10000)
+        socket.on('timeout', () => socket.destroy())
+      })
+    }
   } else {
     // Support static CDN for chunks
     config.output.publicPath = 'auto'