domain,events: support non-object 'error' argument

Fix a TypeError when emitting an 'error' argument with a non-object
argument (like a string) when domains are active.

Fixes: nodejs/help#501
PR-URL: #11438
Reviewed-By: Anna Henningsen <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: James M Snell <[email protected]>

lib/events.js

@@ -153,9 +153,11 @@ EventEmitter.prototype.emit = function emit(type) {
  if (domain) {
  if (!er)
  er = new Error('Uncaught, unspecified "error" event');
- er.domainEmitter = this;
- er.domain = domain;
- er.domainThrown = false;
+ if (typeof er === 'object' && er !== null) {
+ er.domainEmitter = this;
+ er.domain = domain;
+ er.domainThrown = false;
+ }
  domain.emit('error', er);
  } else if (er instanceof Error) {
  throw er; // Unhandled 'error' event

test/parallel/test-event-emitter-no-error-provided-to-error-event.js

@@ -3,12 +3,33 @@ const common = require('../common');
 const assert = require('assert');
 const events = require('events');
 const domain = require('domain');
-const e = new events.EventEmitter();
 
-const d = domain.create();
-d.add(e);
-d.on('error', common.mustCall(function(er) {
- assert(er instanceof Error, 'error created');
-}));
+{
+ const e = new events.EventEmitter();
+ const d = domain.create();
+ d.add(e);
+ d.on('error', common.mustCall(function(er) {
+ assert(er instanceof Error, 'error created');
+ }));
+ e.emit('error');
+}
 
-e.emit('error');
+for (const arg of [false, null, undefined]) {
+ const e = new events.EventEmitter();
+ const d = domain.create();
+ d.add(e);
+ d.on('error', common.mustCall(function(er) {
+ assert(er instanceof Error, 'error created');
+ }));
+ e.emit('error', arg);
+}
+
+for (const arg of [42, 'fortytwo', true]) {
+ const e = new events.EventEmitter();
+ const d = domain.create();
+ d.add(e);
+ d.on('error', common.mustCall(function(er) {
+ assert.strictEqual(er, arg);
+ }));
+ e.emit('error', arg);
+}