Uncaught Error: Cannot find module 'underscore'

Hi everyone,

I was following the tutorial to build clapper-p2phls-plugin. Everything went well except when it came to run the demo. I'm getting the following error even though underscore.js is correctedly linked.

Uncaught Error: Cannot find module 'underscore'

Has anyone else met this problem before? I'll appreciate any solution and comments.

Thanks