message: Create ERROR_SCAN_UNKNOWN
diff: @@ -64,9 +64,12 @@ static ERROR_DB_UNKNOWN: i32 = -1_000_502;
  // The 2_xxx_xxx namespace is reserved for #[cfg(feature = "iterator")]
  +/// An unknown error in the db_scan implementation
  +#[cfg(feature = "iterator")]
  +static ERROR_SCAN_UNKNOWN: i32 = -2_000_001;
  /// Invalid Order enum value passed into scan
  #[cfg(feature = "iterator")]
  -static ERROR_SCAN_INVALID_ORDER: i32 = -2_000_001;
  +static ERROR_SCAN_INVALID_ORDER: i32 = -2_000_002;
  /// An unknown error in the db_next implementation
  #[cfg(feature = "iterator")]
  static ERROR_NEXT_UNKNOWN: i32 = -2_000_101;
  @@ -262,11 +265,11 @@ pub fn do_scan<S: Storage + 'static, Q: Querier>(
  let new_id = set_iterator::<S, Q>(ctx, iterator);
  match to_i32(new_id) {
  Ok(new_id_signed) => new_id_signed,
  - Err(_) => ERROR_DB_UNKNOWN,
  + Err(_) => ERROR_SCAN_UNKNOWN,
  }
  }
  Err(VmError::UninitializedContextData { .. }) => ERROR_NO_CONTEXT_DATA,
  - Err(_) => ERROR_DB_UNKNOWN,
  + Err(_) => ERROR_SCAN_UNKNOWN,
  }
  }
  