Skip failing application.js link check

When the hyperlink package tries to check the application.js it will parse the code
so it can look for additional links to try.
When it does this it fails when it encounters optional chaining syntax (`?.`)
this is because the parser does not support it yet.

This skip can be removed when this support is added and shipped:
estools/estraverse#112

See also #577 (comment)

Author: NickColley

package.json

@@ -9,7 +9,7 @@
     "build:sassdocv5": "sassdoc --no-update-notifier --parse node_modules/govuk-frontend-v5/dist/govuk/ > data/sassdoc-v5.json",
     "build:sassdocv4": "sassdoc --no-update-notifier --parse node_modules/govuk-frontend-v4/govuk/ > data/sassdoc-v4.json",
     "lint": "standard",
-    "check-links": "hyperlink --canonicalroot https://frontend.design-system.service.gov.uk --internal --recursive build/index.html --skip 'property=\"og:image\"' | tee check-links.log | tap-mocha-reporter min"
+    "check-links": "hyperlink --canonicalroot https://frontend.design-system.service.gov.uk --internal --recursive build/index.html --skip 'property=\"og:image\"' --skip 'application.js' | tee check-links.log | tap-mocha-reporter min"
   },
   "devDependencies": {
     "govuk-frontend": "^6.1.0",