server.mjs

import express from "express";
import process from "process";

async function main() {
    const app = express();
    const port = 3000;

    app.get("/hello", (req, res) => {
        res.send("Hello World!");
    });

    app.get("/error", (req, res) => {
        throw new Error("hmm");
    });

    app.get("/async-error", async function (req, res, next) {
        await doAsyncError();
    });
    app.get("/async-error2", async function (req, res, next) {
        doAsyncError().catch(next);
    });
    app.get("/async-error3", async function (req, res, next) {
        try {
            await doAsyncError();
        } catch (err) {
            next(err);
        }
    });

    app.use(function (err, req, res, next) {
        log({ level: "error", err });
        res.setHeader("content-type", "application/json");
        res.status(500).send({ msg: "An error occurred", err });
    });

    app.listen(port, () => {
        log({ msg: `start on port ${port}.` });
    });
}

async function doAsyncError() {
    try {
        return await new Promise((resolve, reject) => {
            setTimeout(() => {
                reject(new Error("Something went wrong"));
            }, 1000);
        });
    } catch (err) {
        console.log("catch: **%s**", err)
        throw err;
    }
}

function log({ level = "info", msg, err }) {
    if (err) {
        console.log("========================================")
        console.error(err);
        console.log("========================================")
    } else {
        console.log("----------------------------------------")
        console.log(`${level}: ${msg}`);
        console.log("----------------------------------------")
    }
}

main().then(() => console.log("done")).catch((e) => { console.error(e); process.exit(1); });