Revert "events: allow monitoring error events"

This reverts commit 5cb0de9.

doc/api/events.md

@@ -155,18 +155,6 @@ myEmitter.emit('error', new Error('whoops!'));
 // Prints: whoops! there was an error
 ```
 
-It is possible to monitor `'error'` events without consuming the emitted error
-by installing a listener using the symbol `errorMonitor`.
-
-```js
-const myEmitter = new MyEmitter();
-myEmitter.on(EventEmitter.errorMonitor, (err) => {
-  MyMonitoringTool.log(err);
-});
-myEmitter.emit('error', new Error('whoops!'));
-// Still throws and crashes Node.js
-```
-
 ## Capture Rejections of Promises
 
 > Stability: 1 - captureRejections is experimental.
@@ -360,19 +348,6 @@ the event emitter instance, the event’s name and the number of attached
 listeners, respectively.
 Its `name` property is set to `'MaxListenersExceededWarning'`.
 
-### `EventEmitter.errorMonitor`
-<!-- YAML
-added: v12.16.0
--->
-
-This symbol shall be used to install a listener for only monitoring `'error'`
-events. Listeners installed using this symbol are called before the regular
-`'error'` listeners are called.
-
-Installing a listener using this symbol does not change the behavior once an
-`'error'` event is emitted, therefore the process will still crash if no
-regular `'error'` listener is installed.
-
 ### `emitter.addListener(eventName, listener)`
 <!-- YAML
 added: v0.1.26

lib/events.js

@@ -60,7 +60,6 @@ const {
 } = require('internal/util/inspect');
 
 const kCapture = Symbol('kCapture');
-const kErrorMonitor = Symbol('events.errorMonitor');
 
 function EventEmitter(opts) {
   EventEmitter.init.call(this, opts);
@@ -90,13 +89,6 @@ ObjectDefineProperty(EventEmitter, 'captureRejections', {
   enumerable: true
 });
 
-ObjectDefineProperty(EventEmitter, 'errorMonitor', {
-  value: kErrorMonitor,
-  writable: false,
-  configurable: true,
-  enumerable: true
-});
-
 // The default for captureRejections is false
 ObjectDefineProperty(EventEmitter.prototype, kCapture, {
   value: false,
@@ -270,11 +262,9 @@ EventEmitter.prototype.emit = function emit(type, ...args) {
   let doError = (type === 'error');
 
   const events = this._events;
-  if (events !== undefined) {
-    if (doError && events[kErrorMonitor] !== undefined)
-      this.emit(kErrorMonitor, ...args);
+  if (events !== undefined)
     doError = (doError && events.error === undefined);
-  } else if (!doError)
+  else if (!doError)
     return false;
 
   // If there is no 'error' event listener then throw.