message: error message for unexpected length of did returns base58 converted length.
diff: @@ -365,7 +365,9 @@ impl CryptoService {
  Vec::from_hex(seed)
  .to_indy(IndyErrorKind::InvalidStructure, "Seed is invalid hex")?
  } else {
  - return Err(err_msg(IndyErrorKind::InvalidStructure, "Invalid Seed length"));
  + return Err(err_msg(IndyErrorKind::InvalidStructure,
  + format!("Trying to use invalid `seed`. It can be either \
  + {} bytes string or base64 string or {} bytes HEX string", ed25519_sign::SEEDBYTES, ed25519_sign::SEEDBYTES * 2)));
  };
  let res = ed25519_sign::Seed::from_slice(bytes.as_slice())?;
  @@ -409,7 +411,8 @@ impl CryptoService {
  let did = base58::decode(did)?;
  if did.len() != 16 && did.len() != 32 {
  - return Err(err_msg(IndyErrorKind::InvalidStructure, format!("Trying to use did with unexpected len: {}", did.len())));
  + return Err(err_msg(IndyErrorKind::InvalidStructure,
  + format!("Trying to use `did` with unexpected length: {}. The length of base58-decoded `did` must be either 16 or 32 bytes.", did.len())));
  }
  let res = ();
  