message: Comment on Error and Result
diff: @@ -3,6 +3,8 @@ use snafu::Snafu;
  #[derive(Debug, Snafu)]
  #[snafu(visibility = "pub")]
  +/// Structured error type for init, handle and query. This cannot be serialized to JSON, such that
  +/// it is only available within the contract and its unit tests.
  pub enum Error {
  #[snafu(display("Invalid Base64 string: {}", source))]
  Base64Err {
  @@ -60,6 +62,8 @@ pub enum Error {
  },
  }
  +/// Result for init, handle and query. Since the error type cannot be serialized to JSON,
  +/// this is only available within the contract and its unit tests.
  pub type Result<T, E = Error> = core::result::Result<T, E>;
  pub fn invalid<T>(field: &'static str, msg: &'static str) -> Result<T> {
  