AddOn (SDK) & socket.io : Object is undefined

Hi,

I try to use socket.io (client) in my main (background) script.
But I face an error I can’t fix :
JPM [error] Message: TypeError: Object is undefined
Stack:
runInContext@resource://gre/modules/commonjs/toolkit/loader.js -> resource://stopphishing/lib/verifrombg.js -> resource://stopphishing/data/js/socket.io.js:6381:9

I can’t explain why the Object class is undefined.

The PageWorker “trick” is the only way to use socket.io in a FF AddOn ?

Thanks