Node.js Error Handling

const fs = require("fs");

try {
  fs.readFileSync("/definitely/not/here.txt");
} catch (err) {
  console.log(err.code, err.syscall);
}

class AppError extends Error {
  constructor(message, status) {
    super(message);
    this.name = "AppError";
    this.status = status;
  }
}

try {
  throw new AppError("User not found", 404);
} catch (err) {
  console.log(err instanceof AppError, err.name, err.status, err.message);
}

fs.readFile("/nope.txt", (err, data) => {
  console.log("callback error:", err.code, data);
});

process.on("uncaughtException", (e) => console.log("last resort:", e.message));
setTimeout(() => { throw new Error("late failure"); }, 20);

ENOENT open
true AppError 404 User not found
callback error: ENOENT undefined
last resort: late failure