Chromium refuses minified code (‘not utf-8’)

package.json

@@ -10,6 +10,8 @@
   "scripts": {
     "dev": "webextension-toolbox dev",
     "build": "webextension-toolbox build",
+    "build-all": "npm run build firefox && npm run build-chrome",
+    "build-chrome": "webextension-toolbox build --no-minimize chrome",
     "test": "ava"
   },
   "devDependencies": {