Update webpack for development mode, add trailing comma in webpack configuration

Author: jake-pauls

ui-svelte-starter/package.json

@@ -2,8 +2,8 @@
   "name": "com.adobe.uxp.starter.svelte",
   "version": "1.0.0",
   "scripts": {
-    "watch": "webpack -w --mode production",
-    "build": "webpack --mode production"
+    "watch": "webpack -w --mode development",
+    "build": "webpack --mode development"
   },
   "license": "none",
   "private": true,

ui-svelte-starter/webpack.config.js

@@ -40,6 +40,6 @@ module.exports = {
   plugins: [
     new CopyPlugin({
       patterns: ['plugin'],
-    })
+    }),
   ],
 };