Koa.js | Typescript implementation of problem details

import Koa from "koa";
import createError from "http-errors"; // https://www.npmjs.com/package/http-errors
import {
	problemDetailsMiddleware,
	ProblemDetailsException,
	ProblemDetails,
} from "rfc-7807-problem-details";
const app = new Koa();

// Should come at the beginning of the middleware chain
// https://github.com/koajs/koa/blob/master/docs/error-handling.md
app.use(
	problemDetailsMiddlewareOb.koa((options) => {
		// createError function returns instance of HttpError hence we need to map it to problem details
		options.map(createError.HttpError, (error) => {
			return new ProblemDetails(
				error.type,
				error.message,
				error.status,
				error.detail
			);
		});
	})
);

app.use(async (ctx, next) => {
	switch (ctx.originalUrl) {
		case "/example/throw":
			throw new ProblemDetailsException({
				type: "cannot-proceed",
				status: 400,
				title: "You cannot proceed.",
			});
		case "/example/custom/throw":
			throw createError(400, "You cannot proceed.", {
				type: "cannot-proceed",
				detail: `some more details about the error - human friendly error`,
			});
		default:
			ctx.body = "Hello World";
			break;
	}
	await next();
});

const server = app.listen(3000);