Stage after merging with project files

src/middleware/errorHandler.js

@@ -0,0 +1,15 @@
+export function notFoundHandler(_req, res) {
+  res.status(404).json({ message: 'Route not found.' });
+}
+
+export function errorHandler(error, _req, res, _next) {
+  const statusCode = error.statusCode || 500;
+
+  if (statusCode >= 500) {
+    console.error(error);
+  }
+
+  res.status(statusCode).json({
+    message: error.message || 'Unexpected server error.'
+  });
+}