message: put the failing did into the error
diff: @@ -217,7 +217,7 @@ impl DidCommandExecutor {
  let (did, key) = self.crypto_service.create_my_did(&my_did_info)?;
  if self.wallet_service.record_exists::<Did>(wallet_handle, &did.did)? {
  - return Err(IndyError::DidError(DidError::AlreadyExistsError("Did already exists".to_string())));
  + return Err(IndyError::DidError(DidError::AlreadyExistsError(did.to_string())));
  };
  self.wallet_service.add_indy_object(wallet_handle, &did.did, &did, &HashMap::new())?;
  