HTTP server error handler in Typescript and Node.js

Question

I'm transforming Typescript for my backend codebase, but when listening to http server Error Event, I'm facing an issue about [ts] property syscall does not exist on error. I think the Error type is wrong here, but apparently Node.js does not provide the default error type for this callback function. Anyone can help me with the correct Error type?

const http = require('http');
const server = http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.write('Hello World!');
  res.end();
})

server.listen(3000);
server.on('error', onError);

function onError(error: Error) {
  // [ts] property syscall does not exist on error
  if (error.syscall !== 'listen') {
    throw error;
  }
}

Answer 1

Trying changing the type of your error variable from Error to NodeJS.ErrnoException. This type is an interface that extends the base Error interface and adds the syscall property, among others.

Source: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/node/index.d.ts#L401

export interface ErrnoException extends Error {
    errno?: number;
    code?: string;
    path?: string;
    syscall?: string;
    stack?: string;
}

Answer 2

If you're using types, like @types/node, the class you want to use is NodeJS.ErrnoException. Saying use any to solve the problem of lacking a type, is the same as saying if you want to stop punctures on a car, take off the wheels.