PDF.js version: 3.5.141

These two properties should be marked as not mandatory as they are initialized if not present
if (!this.pdfDocument) {
      return Promise.resolve(null);
    }
    if (!this._optionalContentConfigPromise) {
      console.error("optionalContentConfigPromise: Not initialized yet.");
      
      
      return this.pdfDocument.getOptionalContentConfig();
    }
    return this._optionalContentConfigPromise;
  }
  /**
   * @param {Promise<OptionalContentConfig>} promise - A promise that is
   *   resolved with an {@link OptionalContentConfig} instance.
   */
  set optionalContentConfigPromise(promise) {