How to access files in static directory using the domain (nuxtjs project)?

Question

I have a third party library js file (called: sw.js) that have to been put on the static directory inside my nuxtjs project so that It can be accessed through our domain as follows www.example.com/sw.js, but this doesn't work.

However I put the sitemap.xml file at the same directory beside the sw.js file and the sitemap file can be accessed easily through www.example.com/sitemap.xml, and what is more interesting is the sw.js file can be accessed locally through localhost:3000/sw.js but never on production.

Is the problem with the file itself or with something else ?

website is deployed on heroku