Reproducer for swagger-codegen issue 4819.
Make sure you install all requirements:
npm install
then run the server:
node server.js
It will offer a RESTful API on http://localhost:5000/ping which you can test.
Then please open: http://localhost:5000/index.html and look at JavaScript console.
Note that the bundle.js file was created using browserify, as explained in the swagger-codegen client's README.me file.