The provided prices have mismatched currencies

This also happens in the frontend, I suggested a different message, also don't know if we could use the order total currency code or is potentially not set at this point?
As suggested when detecting a different currency code, we can break the order items loop as well.

Also marking this as "needs work" as tests are failing. There are recent test failures that are unrelated but the OrderAdminTest is also failing and that is due to this change.