slapos_accounting: use Software Product

master/bt5/slapos_accounting/SkinTemplateItem/portal_skins/slapos_accounting/InstanceTree_requestUpdateOpenSaleOrder.py

@@ -130,7 +130,7 @@ if instance_tree.getCausalityState() == 'diverged':
         default=None,
       )
       if price is None:
-        raise NotImplementedError('Price must be defined')
+        raise NotImplementedError('Price not found on %s' % open_sale_order.getSpecialise())
       open_order_line.edit(
         price=price
       )