It seems that it has a problem with a particular items property, it looks like the SKU is the problem.
Do you experience this issue on any other page in the site? If so what other pages? As a test make a new blank page and apply an eCart display manager to the page. Try adding items to your cart then visit this display manager page to see if you get the same error.
The error is coming from the definition file for the display info code. It seems that it must be failing when it gets to this part. When you get to the confirm page you can see it the first time through correct? Is there a particular item that you have in the cart when you test this and get the error?