function _standardizeCode (code) {
  if (code === 'Neo.TransientError.Transaction.Terminated') {
    return 'Neo.ClientError.Transaction.Terminated'
  } else if (code === 'Neo.TransientError.Transaction.LockClientStopped') {
    return 'Neo.ClientError.Transaction.LockClientStopped'
  }
  return code
}
Standardize error classification that are different between 5.x and previous versions.

The transient error were clean-up for being retrieable and because of this
`Terminated` and `LockClientStopped` were reclassified as `ClientError`.

@param {string} code
@returns {string} the standardized error code