MemoryCryptoStore probably never gets used

[foldleft]

I'm not convinced that LocalStorage ever falls back to a MemoryStore.

Here's how the fallback happens:

            try {
                return new LocalStorageCryptoStore(global.localStorage);
            } catch (e) {
                logger.warn(
                    `unable to open localStorage: falling back to in-memory store: ${e}`,
                );
                return new MemoryCryptoStore();
            }

Here's the constructor we expect to throw:

export class LocalStorageCryptoStore extends MemoryCryptoStore {
    constructor(webStore) {
        super();
        this.store = webStore;
    }
    ...
}

[bwindels]

Should we update the title to MemoryCryptoStore?