Hi again,
Just tried:
Added first a single product to cart, then deleted it from cart. All fine.
Added two products to cart, deleted one after the other. All fine.
No site 'crash'.
But you have a different problem:
As soon as anything gets added to the cart, an "invisible" popup of immense size blocks out the main menu and other stuff.
Its HTML:
<div id="modal-hikashop_print_popup" class="modal hide fade" style="width:780px;height:570px;margin-left:-390px">
You can only make it visible by removing the class "fade" (which has a "top:-25%;" from bootstrap.css, so it slides down a bit when "fade" is removed), and then it looks like in the attached screenshot.
I'm the last one to know where that's coming from, but it seems to be there as soon as something is in the cart, and gone when the cart is empty.
Just thought I'll report the findings as it might speed up the fix of whatever the issue is.