code: function allListeners(state = [], { type, payload }) {
    switch (type) {
      case actionTypes.SET_LISTENER:
        return [...state, payload.name];
      case actionTypes.UNSET_LISTENER:
        return state.filter(name => name !== payload.name);
      default:
        return state;
    }
  }
docs: Reducer for listeners state. Changed by `ERROR` and `LOGOUT` 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
  @return {Object} allListeners state after reduction (used in listeners)
  @private