The build doesn't break when I remove that line and I couldn't reproduce that error. The source here is always a shipment, for shipping adjustments, before and after a `reload`.

Anyway I preferred not to remove it because I think we don't have any spec covering the scenario where we check the object passed here will always be a shipment for shipping adjustments. I tried to come up with something but couldn't make it.

Also I've updated the PR by adding a `update_shipping_adjustments` method so that it doesn't end up passing an order object to shipping calculators.

build is still green