Illustrating a question on how to initialize state in redux

reactReduxDynamicInitialStateExample.js

// How do I initialize state when I do *NOT* want to use hard-coded values?

// in MyComponent.js ...
const mapStateToProps = (state, ownProps) => {
  return {
    usernames: state.MyComponent.usernames,
    selectedDesserts: state.MyComponent.selectedDesserts || ownProps.availableDesserts
  };
};

// in MyComponent.ducks.js ...
const initialState = {
  usernames: [],
  selectedDesserts: null
};

// Then the reducer gets a bit tricky because it has to deal with
// possibility of `selectedDesserts` being either `null` or an
// array that needs to be updated.

// So this feels less than ideal, but how do we initialize `selectedDesserts`
// to be "every available dessert" when we don't know the list of available
// desserts ahead of time?