Uncaught, unspecified 'error' event

[antoine-pous]

Hi !

For the first time i'm facing a problem with EE2, here is the code:

let net = require('net')
let ev = require('eventemitter2').EventEmitter2
let myProject = function(host, port) {
  ev.call(this)
  let self = this
  let socket = net.connect(port, host)
  socket.on("error", function(e) {
    // here
    self.emit("error", "Socket", e.syscall + ' ' + e.errno + ' on ' + e.host + ':' + e.port)
  })
util.inherits(myProject, ev)
exports = module.exports = myProject

Each time i got this error Uncaught, unspecified 'error' event, when i change the event name for any other name the event is correctly emitted.

I don't understand why i have this behavior, this kind of feature works on any other components of my project.

[RangerMauve]

Could you please post the stack trace from the error as well as the version of EE2 you have installed?

[agirorn]

It seems that if you are not listening on the error event when it is emitted EvenEmmiter will throw this error.

The error can be reproduced like this

const EventEmitter2 = require('eventemitter2').EventEmitter2;
const events = new EventEmitter2();

console.log('sending first error event');
try {
  events.emit('error', 'The error data');
} catch(e) {
  console.log('caught error', e);
}

events.on('error', (error) => { console.log('got error event', error); });
console.log('sending second error event');
try {
  events.emit('error', 'The error data');
} catch(e) {
  console.log('caught error', e);
}

sending first error event
caught error Error: Uncaught, unspecified 'error' event.
    at EventEmitter.emit (/home/agirorn/code/test/node_modules/eventemitter2/lib/eventemitter2.js:398:15)
    at Object.<anonymous> (/home/agirorn/code/test/t.js:6:10)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.runMain (module.js:604:10)
    at run (bootstrap_node.js:383:7)
    at startup (bootstrap_node.js:149:9)
sending second error event
got error event The error data

[RangerMauve]

Thanks for the details, sadly I'm a bit busy at the moment, but a PR seems like it wouldn't be too hard to do and would be very much welcome!

[agirorn]

I think think this is a similar case to the uncaught promise exception. When it occurs in node.js it is output to the console and the unhandledRejection event is sent. Could this be similar and somehow use the node.js process.on('warning', cb) Event: 'warning' to notify that this occurred and not throw an error that may end up killing the process?

I checked in node 6.12.0 and the process object is an event emitter object and can be used to do this.

process.on('warning', (m) => console.log(`got warning ${m}`));
process.emit('warning', 'test')
=> got warning test
=> true

Would that be an acceptable solution to this?