Error when selecting an image from my gallery from my Flutter app with image_picker

I am developing an application with Flutter, currently from a button I am accessing my gallery, but when I select the image it should show me the selected image in a widget:

return Scaffold(
  key: scaffoldKey,
  appBar: AppBar(
    title: Text('Producto'),
    actions: <Widget>[
      IconButton(
        icon: Icon( Icons.photo_size_select_actual ),
        onPressed: _seleccionarFoto,
      ),
      IconButton(
        icon: Icon( Icons.camera_alt ),
        onPressed: _tomarFoto,
      )
    ],
  ),
  body: SingleChildScrollView(
    child: Container(
      padding: EdgeInsets.all(15.0),
      child: Form(
        key: formKey,
        child: Column(
          children: <Widget>[
            _mostrarFoto(),
            _crearNombre(),
            _crearPrecio(),
            _crearDisponible(),
            _crearBoton(),
          ],
        ),
      ),
    ),
  ),
);

}

The method that selects the photo

_seleccionarFoto() async {

foto = await ImagePicker.pickImage(
  source: ImageSource.gallery
);

if ( foto != null ) {
  // limpieza

}

setState(() {});

}

The widget that displays the photo:

Widget _mostrarFoto() {

if ( producto.fotoUrl != null ) {
  return Container();
} else {
  return Image(

    image: AssetImage( foto?.path ?? 'assets/no-image.png'),
    height: 300.0,
    fit: BoxFit.cover,

  );
}

}

Selecting the image returns to the widget from where the button was pressed to access the gallery, but it does not show any image and shows the following error:

"Unable to load asset: /storage/emulated/0/WhatsApp/Media/WhatsApp Images/IMG-20200123-WA0049.jpg"

After that the application no longer goes back, I have to restart for it to work again. I would appreciate your help, no matter how small, thank you.