remove raise ShippingError from compute, fix #90

commit 5150d1fd80f44e69464eccd9fd034657933d1d12 taken from 1-3-stable
(cherry picked from commit 7d430039c4f7f06f7457a8abc92adff4fa30265e)

Signed-off-by: Tobias Bohwalli <hi@futhr.io>
Get rspec to at least run...

Help welcome to fix these now..
(cherry picked from commit 1c818e376f89c20e5f59c56ed86e6b53b1587aa4)