BETTERZON-38: Added error handler, preparation for DB accessing

Backend/src/middleware/notFound.middleware.ts

@@ -0,0 +1,12 @@
+import { Request, Response, NextFunction } from "express";
+
+export const notFoundHandler = (
+    request: Request,
+    response: Response,
+    next: NextFunction
+) => {
+
+    const message = "Resource not found";
+
+    response.status(404).send(message);
+};