Function setThing

src/common/definable.ts:82–83

(id: Id, thing: Thing | undefined)

  const getThing = (id: Id): Thing | undefined => mapGet(things, id);

  const setThing = (id: Id, thing: Thing | undefined): IdMap<Thing> =>
    mapSet(things, id, thing) as IdMap<Thing>;

  const addStoreListeners = (id: Id, ...listenerIds: Ids): void => {
    const set = mapEnsure(storeListenerIds, id, setNew);