fix server config

frontend/scripts/serve.js

@@ -1,3 +1,4 @@
+// @ts-check
 // Serve app locally without building with webpack, e.g. for e2e
 const fs = require("fs");
 const path = require("path");
@@ -15,23 +16,36 @@ require("dotenv").config({
   path: dotEnvPath,
 });
 
-const [devConfig] = require("../webpack.dev.js");
+const devConfigs = require("../webpack.dev.js");
+const [devConfig] = devConfigs;
 
 const app = express();
 
-const { devServer } = devConfig;
+/** @type {import('webpack').Configuration['devServer']} */
+const devServer = devConfig.devServer;
 
-devServer.setupMiddlewares([], { app });
+if (!devServer) {
+  throw new Error("Dev server not defined in `webpack.dev.js`");
+}
+
+if (devServer.setupMiddlewares) {
+  // @ts-ignore Express app is compatible with `Server`
+  devServer.setupMiddlewares([], { app });
+}
+
+if (Array.isArray(devServer.proxy)) {
+  devServer.proxy.forEach((proxy) => {
+    app.use(
+      // @ts-ignore
+      proxy.context,
+      createProxyMiddleware({
+        ...proxy,
+        followRedirects: true,
+      }),
+    );
+  });
+}
 
-Object.keys(devServer.proxy).forEach((path) => {
-  app.use(
-    path,
-    createProxyMiddleware({
-      ...devServer.proxy[path],
-      followRedirects: true,
-    }),
-  );
-});
 app.use("/", express.static(distPath));
 app.get("/*", (req, res) => {
   res.sendFile(path.join(distPath, "index.html"));