Replace the both() function with the one below:

jquery.scrollTo.mod-to-support-dyn-offsets.js

function both( val ){
    if(typeof val == 'object') {
      return val;
    } else if(typeof val == 'function') {
      var val = val();
      return typeof val == 'object' ? val : { top: val, left:val };
    } else {
      return typeof val == 'object' ? val : { top:val, left:val };
    }
};