errors: migrate socket_list to internal/errors

Author: Bougarfaoui El houcine

lib/internal/errors.js

@@ -177,6 +177,7 @@ E('ERR_UNKNOWN_STREAM_TYPE', 'Unknown stream file type');
 E('ERR_V8BREAKITERATOR', 'Full ICU data not installed. ' +
   'See https://github.com/nodejs/node/wiki/Intl');
 // Add new errors from here...
+E('ERR_SLAVE_CLOSED_BEFORE_REPLY','Slave closed before reply');
 
 function invalidArgType(name, expected, actual) {
   assert(name, 'name is required');

lib/internal/socket_list.js

@@ -1,5 +1,7 @@
 'use strict';
 
+const errors = require('internal/errors');
+
 const EventEmitter = require('events');
 
 // This object keeps track of the sockets that are sent
@@ -18,7 +20,7 @@ class SocketListSend extends EventEmitter {
 
     function onclose() {
       self.child.removeListener('internalMessage', onreply);
-      callback(new Error('child closed before reply'));
+      callback(new errors.Error('ERR_SLAVE_CLOSED_BEFORE_REPLY'));
     }
 
     function onreply(msg) {