get fileService() {
    if (this.options.fileService) {
      return this.options.fileService;
    }
    if (this.options.formio) {
      return this.options.formio;
    }
    if (this.root && this.root.formio) {
      return this.root.formio;
    }
    const formio = new Formio();
    // If a form is loaded, then make sure to set the correct formUrl.
    if (this.root && this.root._form && this.root._form._id) {
      formio.formUrl = `${formio.projectUrl}/form/${this.root._form._id}`;
    }
    return formio;
  }
Get `Formio` instance for working with files
@returns {import('@formio/core').Formio} - The Formio instance file service.