domain: fix error emit handling

Fix an issue where error is never emitted on the original EventEmitter in situations where a listener for error does exist. Refactor to eliminate unnecessary try/catch/finally block. Backport-PR-URL: #18487 PR-URL: #17588 Refs: #17403 Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: apapirovski

lib/domain.js

@@ -399,32 +399,35 @@ EventEmitter.init = function(){
 consteventEmit=EventEmitter.prototype.emit;
 EventEmitter.prototype.emit=functionemit(...args){
 constdomain=this.domain;
-if(domain===null||domain===undefined||this===process){
-returnReflect.apply(eventEmit,this,args);
-}
 
 consttype=args[0];
-// edge case: if there is a domain and an existing non error object is given,
-// it should not be errorized
-// see test/parallel/test-event-emitter-no-error-provided-to-error-event.js
-if(type==='error'&&args.length>1&&args[1]&&
-!(args[1]instanceofError)){
-domain.emit('error',args[1]);
-returnfalse;
-}
+constshouldEmitError=type==='error'&&
+this.listenerCount(type)>0;
 
-domain.enter();
-try{
+// Just call original `emit` if current EE instance has `error`
+// handler, there's no active domain or this is process
+if(shouldEmitError||domain===null||domain===undefined||
+this===process){
 returnReflect.apply(eventEmit,this,args);
-}catch(er){
-if(typeofer==='object'&&er!==null){
+}
+
+if(type==='error'){
+conster=args.length>1&&args[1] ?
+args[1] : newerrors.Error('ERR_UNHANDLED_ERROR');
+
+if(typeofer==='object'){
 er.domainEmitter=this;
 er.domain=domain;
 er.domainThrown=false;
 }
+
 domain.emit('error',er);
 returnfalse;
-}finally{
-domain.exit();
 }
+
+domain.enter();
+constret=Reflect.apply(eventEmit,this,args);
+domain.exit();
+
+returnret;
 };

test/parallel/test-domain-ee-error-listener.js

@@ -0,0 +1,20 @@
+'use strict';
+
+constcommon=require('../common');
+constassert=require('assert');
+constdomain=require('domain').create();
+constEventEmitter=require('events');
+
+domain.on('error',common.mustNotCall());
+
+constee=newEventEmitter();
+
+constplainObject={justAn: 'object'};
+ee.once('error',common.mustCall((err)=>{
+assert.deepStrictEqual(err,plainObject);
+}));
+ee.emit('error',plainObject);
+
+consterr=newError('test error');
+ee.once('error',common.expectsError(err));
+ee.emit('error',err);