jQuery 1.4.2 fadeIn(), show() Failing in Chrome when using easing plugin 1.3

Question

Recently notice that all fade related content is breaking in Chrome with the error Property "undefined" of object is not a function.

Can anyone by looking at this error thrown in Chrome tell me what is the problem?

Uncaught TypeError: Property 'undefined' of object # is not a function:

swingpublic/javascripts/jquery/jquery.easing-1.3.js:46 
c.fx.steppublic/javascripts/jquery/jquery-1.4.2.min.js:143 
fpublic/javascripts/jquery/jquery-1.4.2.min.js:140 
c.fx.custompublic/javascripts/jquery/jquery-1.4.2.min.js:141 
c.fx.showpublic/javascripts/jquery/jquery-1.4.2.min.js:141 
(anonymous function)public/javascripts/jquery/jquery-1.4.2.min.js:137 
eachpublic/javascripts/jquery/jquery-1.4.2.min.js:30 
(anonymous function)public/javascripts/jquery/jquery-1.4.2.min.js:137 
dequeuepublic/javascripts/jquery/jquery-1.4.2.min.js:40 
(anonymous function)public/javascripts/jquery/jquery-1.4.2.min.js:41 
eachpublic/javascripts/jquery/jquery-1.4.2.min.js:30 
c.fn.c.eachpublic/javascripts/jquery/jquery-1.4.2.min.js:24 
queuepublic/javascripts/jquery/jquery-1.4.2.min.js:41 
animatepublic/javascripts/jquery/jquery-1.4.2.min.js:136 
l.jpublic/javascripts/jquery/jquery.ui.tabs.min.js:13 
(anonymous function)public/javascripts/jquery/jquery.ui.tabs.min.js:13 
dequeuepublic/javascripts/jquery/jquery-1.4.2.min.js:40 
(anonymous function)public/javascripts/jquery/jquery-1.4.2.min.js:41 
eachpublic/javascripts/jquery/jquery-1.4.2.min.js:30 
c.fn.c.eachpublic/javascripts/jquery/jquery-1.4.2.min.js:24 
dequeuepublic/javascripts/jquery/jquery-1.4.2.min.js:41 
m.cpublic/javascripts/jquery/jquery.ui.tabs.min.js:13 
(anonymous function)public/javascripts/jquery/jquery.ui.tabs.min.js:13 
dequeuepublic/javascripts/jquery/jquery-1.4.2.min.js:40 
(anonymous function)public/javascripts/jquery/jquery-1.4.2.min.js:41 
eachpublic/javascripts/jquery/jquery-1.4.2.min.js:30 
c.fn.c.eachpublic/javascripts/jquery/jquery-1.4.2.min.js:24 
dequeuepublic/javascripts/jquery/jquery-1.4.2.min.js:41 
loadpublic/javascripts/jquery/jquery.ui.tabs.min.js:13 
(anonymous function)public/javascripts/jquery/jquery.ui.tabs.min.js:13 
c.event.handlepublic/javascripts/jquery/jquery-1.4.2.min.js:55 
j.handle.opublic/javascripts/jquery/jquery-1.4.2.min.js:49

The code is a simple bind:

var signup = $('.mod-newsletter-signup');
var thanks = $('.mod-newsletter-thanks');
signup.fadeOut('slow',function(){
  thanks
    .hide()
    .removeClass('hide')
    .fadeIn();
});