There are not currently any low-cost airline routes between Gothenburg (Landvetter) and Alicante with Sterling.
Instead you could try browsing budget flights between Gothenburg (Landvetter) and Alicante with all airlines.
Another option would be to try browsing all low-cost airline routes to Alicante or all budget routes from Gothenburg (Landvetter).
In the meantime, this error has been logged.