[BUG] Null check operator used on a null value

[minhnguyenandpad]

Describe the bug
I'm using the PhotoViewGallery.builder
Here the code:
PhotoViewGallery.builder( pageController: widget._pageController, itemCount: widget.urlImages.length, builder: (context, index) { final urlImage = widget.urlImages[index]; return PhotoViewGalleryPageOptions( imageProvider: NetworkImage(urlImage), minScale: PhotoViewComputedScale.contained, maxScale: PhotoViewComputedScale.contained * 4, ); }, onPageChanged: (index) => setState(() => this.index = index,), ),

To Reproduce
When ever go in GalleryWidget, and slide the image => it show this error: Null check operator used on a null value => Then it show the image.

Expected behavior
Stop showing this error

Which versions of Flutter/Photo View, and which browser / OS are affected by this issue? Did this work in previous versions of Photo View?
Lastest version

[renancaraujo]

May be fixed on 0.14.0. See #476