title: Flutter Modal Bottom Sheet with Navigator does not pop as expected
body: <p>I a working with <a href="https://pub.dev/packages/modal_bottom_sheet" rel="nofollow noreferrer">ModalBottomSheet</a> and I love the package. However I am encountering an issue when trying to navigate with in a ModalBottomSheet.</p>
  <p>Here is a <a href="https://gofile.io/d/SWLIAe" rel="nofollow noreferrer">ScreenVideo</a> for a better understanding.</p>
  <p>As you can see the View is presented as a ModalBottomSheet. But when popping it, it is not simply dismissing to the bottom but instead it is popping to some empty screen with a MaterialPage Pop animation.</p>
  <p>I changed my code so I can push with a MaterialPageRoute-Animation inside that ModalBottomSheet. Before that everything was working as expected.</p>
  <p>Here is my Page:</p>
  <pre><code>    class _AboutScreenState extends State&lt;AboutScreen&gt; {
    @override
    Widget build(BuildContext context) {
      return Material(
        color: AppColors.primary,
        child: Navigator(
          onGenerateRoute: (settings) =&gt; MaterialPageRoute(
            builder: (context2) =&gt; Builder(
              builder: (context) =&gt; CupertinoPageScaffold(
                  backgroundColor: AppColors.secondary,
                  resizeToAvoidBottomInset: false,
                  child: SafeArea(
                    child: Padding(
                      padding: EdgeInsets.all(sidePadding),
                      child: Column(
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Row(
                            mainAxisAlignment: MainAxisAlignment.end,
                            children: [
                              IconButtonWithExpandedTouchTarget(
                                onTapped: () {
                                  Navigator.pop(context);
                                },
                                svgPath: 'assets/icons/down.svg',
                              ),
                            ],
                          ),
                          Text(
                            'About',
                            style: AppTextStyles.montserratH2SemiBold,
                          ),
  
                          ...
  
                          RoundedCornersTextButton(
                            title: 'Impressum',
                            onTap: () {
                              Navigator.pop(context);
                            },
                            textColor: AppColors.primary,
                            backgroundColor: AppColors.secondary,
                            borderColor: AppColors.primary,
                          ),
                        ],
                      ),
                    ),
                  )),
            ),
          ),
        ),
      );
    }
  }
  </code></pre>
  <p>I was simply following this <a href="https://github.com/jamesblasco/modal_bottom_sheet/blob/master/example/lib/modals/modal_with_navigator.dart" rel="nofollow noreferrer">example</a>. What am I missing here? With the code above I can push inside the ModalSheet as expected with a MaterialPageRoute Animation but popping the first screen brings up the issue...</p>
  <p>Let me know if you need any more info! Any help is appreciated :)</p>