Throwing JS error in Rails6

[siva-wal]

I am trying to integrate swagger in my new rails 6 project. I have added .json files as specified in the documentation. But I facing following error:

manifest.js

//= link_tree ../images
//= link_directory ../javascripts .js
//= link_directory ../stylesheets .css
//= link grape_swagger_rails/application.css
//= link grape_swagger_rails/application.js

Could you let me know where I went wrong?