Fix Webpacker helpers in production env
Fix Webpacker helpers in production env

`Rails.configuration.assets` will be undefined if asset pipeline is not being used, which leads to an error why trying to check the value of `assets.compile`.

This is primarily a problem when using the webpacker helpers (b/c no sprockets) and only in non-dev environments (b/c this logic gets short-circuited if there's a webpack dev server running.)

mileszs/wicked_pdf,bonekost/wicked_pdf