events: load internal/errors eagerly

Since `internal/errors` is loaded by many builtin modules and is
currently the first module loaded during bootstrap, it is
fine to load it eagerly. We just need to make sure
that `internal/errors` itself load other modules lazily.

PR-URL: #26771
Reviewed-By: Yongsheng Zhang <[email protected]>
Reviewed-By: Ruben Bridgewater <[email protected]>

lib/events.js

@@ -23,6 +23,12 @@
 
 var spliceOne;
 
+const {
+  ERR_INVALID_ARG_TYPE,
+  ERR_OUT_OF_RANGE,
+  ERR_UNHANDLED_ERROR
+} = require('internal/errors').codes;
+
 function EventEmitter() {
   EventEmitter.init.call(this);
 }
@@ -42,17 +48,9 @@ EventEmitter.prototype._maxListeners = undefined;
 // added to it. This is a useful default which helps finding memory leaks.
 var defaultMaxListeners = 10;
 
-var errors;
-function lazyErrors() {
-  if (errors === undefined)
-    errors = require('internal/errors').codes;
-  return errors;
-}
-
 function checkListener(listener) {
   if (typeof listener !== 'function') {
-    const errors = lazyErrors();
-    throw new errors.ERR_INVALID_ARG_TYPE('listener', 'Function', listener);
+    throw new ERR_INVALID_ARG_TYPE('listener', 'Function', listener);
   }
 }
 
@@ -63,10 +61,9 @@ Object.defineProperty(EventEmitter, 'defaultMaxListeners', {
   },
   set: function(arg) {
     if (typeof arg !== 'number' || arg < 0 || Number.isNaN(arg)) {
-      const errors = lazyErrors();
-      throw new errors.ERR_OUT_OF_RANGE('defaultMaxListeners',
-                                        'a non-negative number',
-                                        arg);
+      throw new ERR_OUT_OF_RANGE('defaultMaxListeners',
+                                 'a non-negative number',
+                                 arg);
     }
     defaultMaxListeners = arg;
   }
@@ -87,8 +84,7 @@ EventEmitter.init = function() {
 // that to be increased. Set to zero for unlimited.
 EventEmitter.prototype.setMaxListeners = function setMaxListeners(n) {
   if (typeof n !== 'number' || n < 0 || Number.isNaN(n)) {
-    const errors = lazyErrors();
-    throw new errors.ERR_OUT_OF_RANGE('n', 'a non-negative number', n);
+    throw new ERR_OUT_OF_RANGE('n', 'a non-negative number', n);
   }
   this._maxListeners = n;
   return this;
@@ -183,8 +179,7 @@ EventEmitter.prototype.emit = function emit(type, ...args) {
     }
 
     // At least give some kind of context to the user
-    const errors = lazyErrors();
-    const err = new errors.ERR_UNHANDLED_ERROR(stringifiedEr);
+    const err = new ERR_UNHANDLED_ERROR(stringifiedEr);
     err.context = er;
     throw err; // Unhandled 'error' event
   }