Also, add ErrNNSRecordNotFound error that indicates that required hash is not presented in `NNS` contract. Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
Signed-off-by: Alex Vanin <alexey@nspcc.ru>