How to authenticate with v8js script?

Thanks @mrjohny, the link is to our post

I can register a user (user/register), list them (system/user).
The problem is when i try to authenticate a user (user/session), I get an exception.

I explain the problem here:

ps. I tried on two different computers with DF2.0.2 and DF2.0.4, and I received the same error

Thank you!