Dashbook.dualTheme() doesn't assign any value to the variable theme

[bahag-desouzacastror]

Description

I'm trying to access the theme from dashbook and I started receiving null pointers. And them I realised that the constructor Dashbook.dualTheme doesn't assign any value to the variable theme.

This scenario works as expected

final dashbook = Dashbook(
    theme: BahagTheme.light,
  );

dashbook.storiesOf('Colors').decorator(CenterDecorator()).add(
        'Foundation',
        (context) => Padding(
          padding: const EdgeInsets.all(20.0),
          child: Column(
            children: [
              Text(
                'COLORS',
                style: dashbook.theme!.textTheme.headline1!
                    .copyWith(fontSize: 28, color: Colors.black),
              ),

This scenario doesn't work as expected

final dashbook = Dashbook.dualTheme(
    light: BahagTheme.light,
    dark: BahagTheme.dark,
  );

dashbook.storiesOf('Colors').decorator(CenterDecorator()).add(
        'Foundation',
        (context) => Padding(
          padding: const EdgeInsets.all(20.0),
          child: Column(
            children: [
              Text(
                'COLORS',
                style: dashbook.theme!.textTheme.headline1!
                    .copyWith(fontSize: 28, color: Colors.black),
              ),

You can see in the printscreen that the private variable _dualTheme exists with both themes assigned, but the variable theme remains unassigned.