commerce_cart_form_commerce_order_ui_order_form_alter() should only alter the line item manager widget

thanks a lot for your module.
i am trying the commerce kikstart 2 and i watched the video http://commerceguys.com/blog/commerce-module-tuesday-inline-entity-form
there you give instructions for changing the widtet on line items as inline entity form.
if i do so, when i reload the page of a form i get this error in admin/commerce/orders/1/edit

Warning: Invalid argument supplied for foreach() in commerce_cart_form_commerce_order_ui_order_form_alter() (line 327 of /datos/treballs/tarros/tarros/profiles/commerce_kickstart/modules/contrib/commerce/modules/cart/commerce_cart.module).

though it works.
i hope it helps to you.
i have change nothing on the downloaded distribution.
thanks again :)