buildPortrait method Null safety

Implementation

@override
Widget buildPortrait(BuildContext context, final ScreenPositioner screen) {
  return Container(
      alignment: Alignment.center,
      color: deadZoneColor,
      child: AspectRatio(
          aspectRatio: screen.width / screen.height,
          child: Stack(fit: StackFit.expand, children: [
            screen.box(Rect.fromLTWH(0, 0, screen.width, screen.height),
                CustomPaint(painter: DrawnBackground(screen))),
            screen.box(Rect.fromLTWH(0.60, screen.height - 1.5, 0.94, 0.94),
                _jrpnIcon()),
            screen.box(
                const Rect.fromLTWH(
                    0.63, 0.6, 6.7, 1.5 * LcdDisplay.heightTweak),
                LcdDisplay(controller.model, _showMenu)),
            ...controller
                .getPortraitButtonFactory(context, screen)
                .buildButtons(Rect.fromLTRB(
                    0.7, 2.75, screen.width - 0.7, screen.height - 0.47)),
            MainMenu(this, screen)
          ])));
}