undefined is not a constructor
is an error message PhantomJS displays when you tried to call a function that is not defined. It depends on the version of ECMAScript which your PhantomJS supports. So as you said it works fine in Chrome, because this browser supports the function you are using in test.
In order to fix your problem and still be able to use PhantomJS you can replace the “unknown to PhantomJS” function with some alternative function.