HTTP server error handler in Typescript and Node.js

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;
}

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.

This is because not every Error object needs to have a syscall property.

You may be able to fix it changing this:

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

to this:

function onError(error: any) {
  if (error.syscall !== 'listen') {
    throw error;
  }
}

See this issue comments for some background:

• https://github.com/angular/angularfire2/issues/666