How to use the @xviz/io.XVIZEnvelope.Error function in @xviz/io

onStart(msg) {
    // TODO; validation
    const error = null;
    if (error) {
      this.middleware.onError(XVIZEnvelope.Error({message: error}));
    } else {
      // fill in profile, format, session_type
      // make context specific configuration fields
      const message = msg.message();
      if (message.data.message_format) {
        this.context.set('message_format', message.data.message_format);
      } else {
        this.context.set('message_format', 'BINARY');
      }

      if (message.data.profile) {
        this.context.set('profile', message.data.profile);
      } else {
        this.context.set('profile', 'default');
      }

onTransformLog(msg) {
    // TODO: validation
    const error = null;
    if (error) {
      this.middleware.onError(XVIZEnvelope.Error({message: error}));
    } else {
      this._clearActiveTransforms();
      this._startTransform(msg);
    }
  }

onReconfigure(msg) {
    this.middleware.onError(XVIZEnvelope.Error({message: 'Error: reconfigure is not supported.'}));
  }

onTransformPointInTime(msg) {
    this.middleware.onError(
      XVIZEnvelope.Error({message: 'Error: transform_point_in_time is not supported.'})
    );
  }