Sum throws 'Value cannot be null' error on linq query

Sum throws 'Value cannot be null' error on linq query

Linq query fails when trying to sum a decimal: session.Query().Where(x => x.Customer.Id == 4).Sum(x => x.Amount);

nullable로 캐스팅

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Linq query fails when trying to sum a decimal: session.Query().Where(x => x.Customer.Id == 4).Sum(x => (int?)x.Amount) ?? 0;