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.