message: make ledger::Error type implement the Error trait
diff: @@ -209,6 +209,13 @@ fn input_account_verify(
  }
  }
  +impl std::fmt::Display for Error {
  + fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
  + write!(f, "{:?}", self)
  + }
  +}
  +impl std::error::Error for Error {}
  +
  /*
  #[cfg(test)]
  pub mod test {
  