Redux-Saga error while deploying yarn build

Question

i did react-build by yarn

yarn build && serve -s build and i checked web by browser so that i got a lot of error

one of them is the problem using redux-saga

so i did remove this code

export function* channelListSaga() {
    // yield takeLatest(GET_CHANNEL_LIST, getChannelListSaga);
    // yield takeLatest(READ_CHANNEL, readChannelSaga);
}

and then i cant see error and data for channel list too......

certainly i checked doing well in local no bug ... i dont understand why exists the big gap between yarn start and yarn build???

please how can i resolve this problem three times....