Support throw-style errors + auto get port

src/app.ts

@@ -1,5 +1,14 @@
-import express from "express";
+import express from 'express';
+import asyncHandler from 'express-async-handler';
+import APIError, { errorHandler, ErrorCode } from './error';
 
-const app = express();
+const app = express()
+	.get(
+		'/',
+		asyncHandler(async (req, res, next) => {
+			throw new APIError(ErrorCode.NOT_FOUND, 'Route `/` not found');
+		})
+	)
+	.use(errorHandler);
 
 export default app;

src/error.ts

@@ -0,0 +1,39 @@
+import { ErrorRequestHandler } from 'express';
+
+export enum ErrorCode {
+	NOT_FOUND = 'NOT_FOUND',
+}
+
+enum HTTPStatus {
+	NOT_FOUND = 404,
+}
+
+export const errorHandler: ErrorRequestHandler = (error: APIError, req, res, next) => {
+	res.status(error.status);
+
+	const response: any = {
+		error: {
+			code: error.code,
+			message: error.message,
+		},
+	};
+
+	if ((process.env.NODE_ENV = 'development')) {
+		response.error.stack = error.stack;
+	}
+
+	res.json(response);
+};
+
+export default class APIError extends Error {
+	status: HTTPStatus;
+	code: ErrorCode;
+
+	constructor(code: ErrorCode, message: string) {
+		super(message);
+		this.status = HTTPStatus[code] || 500;
+		this.code = code;
+
+		Error.captureStackTrace(this, this.constructor);
+	}
+}

src/server.ts

@@ -1,8 +1,11 @@
-import app from "./app";
-import logger from "./logger";
+import app from './app';
+import logger from './logger';
+import getPort from 'get-port';
 
-const port = process.env.PORT || 3000;
+(async () => {
+	const port = process.env.PORT || (await getPort({ port: 3000 }));
 
-app.listen(port, () => {
-  logger.info(`Server started at port ${port}`);
-});
+	app.listen(port, () => {
+		logger.info(`Server started at port ${port}`);
+	});
+})();