Error with shopping_cart.php when adding items.

I get this error message when trying to add an item to the shopping cart:

Warning: Invalid argument supplied for foreach() in /home/wishgivi/public_html/shop/includes/classes/shopping_cart.php on line 1566

Warning: Cannot modify header information - headers already sent by (output started at /home/wishgivi/public_html/shop/includes/classes/shopping_cart.php:1566) in /home/wishgivi/public_html/shop/includes/functions/functions_general.php on line **44e

**The strange thing is, it still does add the product to the shopping cart. If I go back and visit my shopping cart, the product will be there and I can finish the order, but when the customer adds the product, it shows this message. It only happens when trying to add a product.

I haven't done any real modifications for 2 weeks, the most recent mod I installed was the google base feeder. I tried uninstalling it, but it still gets this error. I also have the imagehandler2, zen lightbox, and cross selling installed, but I don't think those have anything to do with it.

Oh, and I've tried replacing shopping_cart.php and functions_general.php with fresh files from 1.3.7 zip. That didn't do anything

I searched for a similar error and both threads said the culprit was the ultimate SEO URLs mod. I DID have this mod installed a month ago, but I completely uninstalled it. I checked for every file and mySQL table and none of them are here, so that doesn't seem to be the problem..

Not sure about the first error, but for the "Cannot modify header information" error try this:

https://www.zen-cart.com/tutorials/index.php?article=87