constructor(baseDir, options = {}) {
    this.baseDir = baseDir;
    this.options = options;
    /** @type {ComponentList|null} */
    this.components = null;
    /** @type {Object<string, string>} */
    this.libraryIcons = {};
    /** @type {Object<string, Object>} */
    this.sourcesForComponents = {};
    /** @type {Object<string, string>} */
    this.specsForComponents = {};
    /** @type {Promise<ComponentList> | null}; */
    this.processing = null;
    this.ready = false;
  }
@param {string} baseDir
@param {ComponentLoaderOptions} [options]