Why does gulp js work incorrectly?

Question

gulp.js

Good evening.
I have a task for js files.
I am using gulp 4.

gulp.task("js", function () {
  return gulp.src('src/assets/js/main.js')
    .pipe(sourcemaps.init())
    .pipe(babel({
      presets: ['@babel/env']
    }))
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('build/assets/js'))
    .pipe(browserSync.reload({
      stream: true
    }));
});

After collecting the project, an error is displayed and you constantly have to edit it by hand.

let videoGallery = function () {
    $('#js-video-gallery').slick({
      arrows: false,
      dots: false,
      asNavFor: '#js-video-gallery-small'
    });
  };
  videoGallery();

  $('#js-video-gallery-small').slick({
    arrows: false,
    dots: false,
    slidesToShow: 5,
    slidesToScroll: 1,
    asNavFor: '#js-video-gallery',
    focusOnSelect: true
  });
});
sToShow: 5,
    slidesToScroll: 1,
    asNavFor: '#js-video-gallery',
    focusOnSelect: true
  });
});
//# sourceMappingURL=data:application/json;charset=utf8;base64,eyJ2ZXJzaW9uIjozLCJzb3Vy

How to fix it?
Thanks in advance.