fix: defer loading of pretty-error to improve startup time

lib/errors.js

@@ -1,13 +1,22 @@
 // @ts-nocheck
 'use strict';
-const PrettyError = require('pretty-error');
-const prettyError = new PrettyError();
-prettyError.withoutColors();
-prettyError.skipPackage('html-plugin-evaluation');
-prettyError.skipNodeFiles();
-prettyError.skip(function (traceLine) {
-  return traceLine.path === 'html-plugin-evaluation';
-});
+
+let prettyError;
+
+function getPrettyError () {
+  if (!prettyError) {
+    // lazily require to improve startup time since pretty-error is rather heavy package
+    const PrettyError = require('pretty-error');
+    prettyError = new PrettyError();
+    prettyError.withoutColors();
+    prettyError.skipPackage('html-plugin-evaluation');
+    prettyError.skipNodeFiles();
+    prettyError.skip(function (traceLine) {
+      return traceLine.path === 'html-plugin-evaluation';
+    });
+  }
+  return prettyError;
+}
 
 module.exports = function (err, context) {
   return {
@@ -19,7 +28,7 @@ module.exports = function (err, context) {
     },
     toString: function () {
       try {
-        return prettyError.render(err).replace(/webpack:\/\/\/\./g, context);
+        return getPrettyError().render(err).replace(/webpack:\/\/\/\./g, context);
       } catch (e) {
         // This can sometimes fail. We don't know why, but returning the
         // original error is better than returning the error thrown by