Updated the files.

my-app/node_modules/webpack-dev-middleware/dist/utils/setupWriteToDisk.js

@@ -0,0 +1,66 @@
+"use strict";
+
+const fs = require("fs");
+const path = require("path");
+
+/** @typedef {import("webpack").Compiler} Compiler */
+/** @typedef {import("webpack").MultiCompiler} MultiCompiler */
+/** @typedef {import("webpack").Compilation} Compilation */
+/** @typedef {import("../index.js").IncomingMessage} IncomingMessage */
+/** @typedef {import("../index.js").ServerResponse} ServerResponse */
+
+/**
+ * @template {IncomingMessage} Request
+ * @template {ServerResponse} Response
+ * @param {import("../index.js").Context<Request, Response>} context
+ */
+function setupWriteToDisk(context) {
+  /**
+   * @type {Compiler[]}
+   */
+  const compilers = /** @type {MultiCompiler} */
+  context.compiler.compilers || [context.compiler];
+  for (const compiler of compilers) {
+    compiler.hooks.emit.tap("DevMiddleware", () => {
+      // @ts-ignore
+      if (compiler.hasWebpackDevMiddlewareAssetEmittedCallback) {
+        return;
+      }
+      compiler.hooks.assetEmitted.tapAsync("DevMiddleware", (file, info, callback) => {
+        const {
+          targetPath,
+          content
+        } = info;
+        const {
+          writeToDisk: filter
+        } = context.options;
+        const allowWrite = filter && typeof filter === "function" ? filter(targetPath) : true;
+        if (!allowWrite) {
+          return callback();
+        }
+        const dir = path.dirname(targetPath);
+        const name = compiler.options.name ? `Child "${compiler.options.name}": ` : "";
+        return fs.mkdir(dir, {
+          recursive: true
+        }, mkdirError => {
+          if (mkdirError) {
+            context.logger.error(`${name}Unable to write "${dir}" directory to disk:\n${mkdirError}`);
+            return callback(mkdirError);
+          }
+          return fs.writeFile(targetPath, content, writeFileError => {
+            if (writeFileError) {
+              context.logger.error(`${name}Unable to write "${targetPath}" asset to disk:\n${writeFileError}`);
+              return callback(writeFileError);
+            }
+            context.logger.log(`${name}Asset written to disk: "${targetPath}"`);
+            return callback();
+          });
+        });
+      });
+
+      // @ts-ignore
+      compiler.hasWebpackDevMiddlewareAssetEmittedCallback = true;
+    });
+  }
+}
+module.exports = setupWriteToDisk;