Style: extra linting

package.json

@@ -65,7 +65,8 @@
     "plist": "^2.0.1",
     "rimraf": "^2.5.2",
     "run-series": "^1.1.4",
-    "standard": "*"
+    "standard": "*",
+    "walk-sync": "^0.3.1"
   },
   "engines": {
     "node": ">=4.0.0"
@@ -98,7 +99,7 @@
     "package": "node ./bin/package.js",
     "prepublish": "npm run build",
     "start": "npm run build && electron .",
-    "test": "standard && depcheck --ignores=babel-cli,nodemon,gh-release --ignore-dirs=build,dist",
+    "test": "standard && depcheck --ignores=babel-cli,nodemon,gh-release --ignore-dirs=build,dist && node ./bin/extra-lint.js",
     "gh-release": "gh-release",
     "update-authors": "./bin/update-authors.sh",
     "watch": "nodemon --exec 'npm run start' --ext js,pug,css"