Add backend setup with Docker, Express, and error handling page

backend/server.js

@@ -0,0 +1,25 @@
+import express from "express";
+import cors from "cors";
+const app = express();
+const port = 8002;
+
+app.use(cors());
+// Increase body size limits to support large CSV JSON payloads
+app.use(express.urlencoded({ extended: true, limit: "10mb" }));
+app.set("view engine", "ejs");
+app.use(express.json({ limit: "10mb" }));
+
+app.get("/", (req, res) => {
+  res.status(502).render("index.ejs");
+});
+
+app.listen(port, () => {
+  console.log(`Server is running on port: ${port}`);
+});
+
+// error handling code
+app.use((err, req, res, next) => {
+  // Log the error stack and send a generic error response
+  console.error(err.stack);
+  res.status(500).send("Something broke!");
+});