Express doesn’t natively handle promises, which can lead to unhandled rejections. A type-safe wrapper helps:

// Define a wrapper for async route handlers
function asyncHandler<P = ParamsDictionary, ResBody = any, ReqBody = any, ReqQuery = ParsedQs>(
	handler: (
		req: Request<P, ResBody, ReqBody, ReqQuery>,
		res: Response<ResBody>,
		next: NextFunction,
	) => Promise<void>,
): RequestHandler<P, ResBody, ReqBody, ReqQuery> {
	return (req, res, next) => {
		Promise.resolve(handler(req, res, next)).catch(next);
	};
}

// Use it with async routes
app.get(
	'/users/:id',
	asyncHandler<{ id: string }, UserResponse>(async (req, res) => {
		const user = await getUserById(req.params.id);

		if (!user) {
			return res.status(404).json({ error: 'User not found' } as any);
		}

		res.json(user);
	}),
);

This pattern ensures that any errors in async handlers are properly passed to Express’s error handling middleware.