function mapStateToProps (state) {
  return {
    auth: {
      form: {
        isFetching: state.auth.form.isFetching
      }
    },
    global: {
      currentState: state.global.currentState,
      showState: state.global.showState
    }
  }
}
Instead of including all app states via ...state
 One could explicitly enumerate only those which Main.js will depend on.