extracted widget after the null value has been tested

[stephane-archer]

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    LutPreviewFail? lutPreviewFail = _lutPreviewResult.lutPreviewFail;
    if (lutPreviewFail != null) {
      return Tooltip( // extract widget
        message: lutPreviewFail.stdout +
            lutPreviewFail.stderr +
            lutPreviewFail.exitCode.toString(),
        child: const _NoImagePlaceholderWidget(),
      );
    }

extracted widget:

class LutPreviewFailWidget extends StatelessWidget {
  const LutPreviewFailWidget({
    super.key,
    required this.lutPreviewFail,
  });

  final LutPreviewFail? lutPreviewFail;

  @override
  Widget build(BuildContext context) {
    return Tooltip(
      message: lutPreviewFail.stdout +
          lutPreviewFail.stderr +
          lutPreviewFail.exitCode.toString(),
      child: const _NoImagePlaceholderWidget(),
    );
  }
}

expected code:

class LutPreviewFailWidget extends StatelessWidget {
  const LutPreviewFailWidget({
    super.key,
    required this.lutPreviewFail,
  });

  final LutPreviewFail lutPreviewFail;

  @override
  Widget build(BuildContext context) {
    return Tooltip(
      message: lutPreviewFail.stdout +
          lutPreviewFail.stderr +
          lutPreviewFail.exitCode.toString(),
      child: const _NoImagePlaceholderWidget(),
    );
  }
}