build(dev-deps): update to use terser instead of uglifyjs

package.json

@@ -43,11 +43,11 @@
     "ws": "^6.0.0"
   },
   "peerDependencies": {
+    "@discordjs/uws": "^10.149.0",
     "bufferutil": "^4.0.0",
     "erlpack": "discordapp/erlpack",
     "libsodium-wrappers": "^0.7.3",
     "sodium": "^2.0.3",
-    "@discordjs/uws": "^10.149.0",
     "zlib-sync": "^0.1.4"
   },
   "devDependencies": {
@@ -55,10 +55,10 @@
     "discord.js-docgen": "discordjs/docgen",
     "eslint": "^5.4.0",
     "json-filter-loader": "^1.0.0",
+    "terser-webpack-plugin": "^1.1.0",
     "tslint": "^5.11.0",
     "tslint-config-typings": "^0.3.1",
     "typescript": "^3.0.1",
-    "uglifyjs-webpack-plugin": "^1.3.0",
     "webpack": "^4.17.0",
     "webpack-cli": "^3.1.0"
   },

webpack.config.js

@@ -1,6 +1,6 @@
 const path = require('path');
 const webpack = require('webpack');
-const UglifyJSPlugin = require('uglifyjs-webpack-plugin');
+const TerserJSPlugin = require('terser-webpack-plugin');
 const version = require('./package.json').version;
 
 const prod = process.env.NODE_ENV === 'production';
@@ -46,12 +46,13 @@ module.exports = {
   },
   optimization: {
     minimizer: [
-      new UglifyJSPlugin({
-        uglifyOptions: {
+      new TerserJSPlugin({
+        terserOptions: {
           mangle: { keep_classnames: true },
           compress: { keep_classnames: true },
           output: { comments: false },
         },
+        parallel: true,
       }),
     ],
   },