pub async fn rollback(self) -> DalResult<()> {
        match self.inner {
            ConnectionInner::Transaction {
                transaction: postgres,
                tags,
            } => postgres
                .rollback()
                .await
                .map_err(|err| DalConnectionError::rollback_transaction(err, tags.cloned()).into()),
            ConnectionInner::Pooled(conn) => {
                let err = io::Error::other(
                    "`Connection::rollback()` can only be invoked after calling `Connection::begin_transaction()`",
                );
                Err(
                    DalConnectionError::rollback_transaction(sqlx::Error::Io(err), conn.tags)
                        .into(),
                )
            }
        }
    }
Rolls back a transactional connection (one which was created by calling [`Self::start_transaction()`]).
If this connection is not transactional, returns an error.
core/lib/db_connection/src/connection.rs