var jobTitle = _crewService
               .GetCrewPositionTypesResults(x =>
                x.CrewPositionTypeId == addNewCrewMemberViewModel.CrewPositionTypeId)
               .FirstOrDefault()?.Name;

var jobTitle = _crewService
           .GetCrewPositionTypesResults(x =>
            x.CrewPositionTypeId == addNewCrewMemberViewModel.CrewPositionTypeId)
           .FirstOrDefault() != null ? _crewService
           .GetCrewPositionTypesResults(x =>
            x.CrewPositionTypeId == addNewCrewMemberViewModel.CrewPositionTypeId)
           .FirstOrDefault().Name : null;