The source of this is deep down in SG code, as a recent change in the Rhino scripting engine has changed the way different versions of functions are chosen. I have fixed this now and will release a new version of the plugin soon. As there are some other issues with the plugin I would like to wait for these things to clarify a bit so they can be fixed as well before releasing a new version.
But I attached an updated version of js.jar here, to be replaced inside Scriptographer/Core/Java/lib, so you can start using the script already now.