IE 7 javascript errors on the page that display the categories

IE 7 javascript errors on the page that display the categories
IE says line 177

If a choose to open the debugger I get the error here:

/**
 * Adds a function to the window onload event
 */
function addLoadEvent(func) {
  var oldOnload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func; //HERE IS WHERE IT SAYS THE PROBLEM IS
  }
  else {
    window.onload = function() {
      oldOnload();
      func();
    }
  }
}

Looks like other have reported errors with IE long time ago...