constructor({model, cache}) {
        this.activeThemeName = null;

        /** @private */
        this._activatingPromise = null;
        this._activatingName = null;
        this._activatingSettings = null;

        this._repository = new BREAD({model});
        this._valueCache = cache;
        this._activeThemeSettings = {};
    }
@param {Object} options
@param {any} options.model - Bookshelf-like model instance for storing theme setting key/value pairs
@param {import('./CustomThemeSettingsCache')} options.cache - Instance of a custom key/value pair cache