Is there an potential bug with the Reducers in Section 26

[mickeypuri]

In 26. Normalizing API Responses with normalizer

The byId Reducer goes from

switch (action.type) {
    case 'FETCH_TODOS_SUCCESS': // eslint-disable-line no-case-declarations
      const nextState = { ...state };
      action.response.forEach(todo => {
        nextState[todo.id] = todo;
      });
      return nextState;
    case 'ADD_TODO_SUCCESS':
      return {
        ...state,
        [action.response.id]: action.response,
      };
    default:
      return state;
  }
};

to

const byId = (state = {}, action) => {
  if (action.response) {
    return {
      ...state,
      ...action.response.entities.todos,
    };
  }
  return state;
};

However my understanding is that ALL the actions are taken thru ALL the reducers.

So by removing the check for Action Type of 'FETCH_TODOS_SUCCESS' and 'ADD_TODO_SUCCESS' and simply checking if the action contains a response field, then I'm thinking, that what if our system has some other unrelated action that also returns a promise with a response field, and so in that scenario, our byId Reducer would also attempt to handle this unrelated action, which would be a bug.

Am I correct here, or have I missed something?