function authErrorReducer(state = null, action) {
  switch (action.type) {
    case LOGIN:
    case LOGOUT:
      return null
    case LOGIN_ERROR:
    case UNAUTHORIZED_ERROR:
      return action.authError
    default:
      return state
  }
}
Reducer for authError state. Changed by `LOGIN`, `LOGOUT`, `LOGIN_ERROR`, and
`UNAUTHORIZED_ERROR` actions.
@param  {object} [state={}] - Current authError redux state
@param  {object} action - Object containing the action that was dispatched
@param  {string} action.type - Type of action that was dispatched
@returns {object} authError state after reduction