devex: reduce webpack verbosity

src/emulator/package.json

@@ -4,7 +4,7 @@
   "main": "index.js",
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
-    "start-webpack": "webpack --watch --devtool source-map"
+    "start-webpack": "webpack --watch --devtool source-map --stats=errors-only"
   },
   "keywords": [],
   "author": "",