How to Use provider to update the bottom navbar icon and text color

i am new to flutter and was trying the day / night mode theme for the test app i am trying to build. i was able to bring the functionality to hello world app with switch. now my next huddle is the bottom navbar.

how switching the theme from light to dark or dark to light, i want the bottom navbar icon and text to reflect the changes. how can i achieve that ?

below is my code for the bottom navbar:

Padding bottomNav() {

final theme = Provider.of<ThemeChanger>(context);

return Padding(
  padding: EdgeInsets.only(top: 10, bottom: 5),
  child: BubbleBottomBar(
    backgroundColor: Colors.transparent,
    opacity: 1,
    elevation: 0,
    currentIndex: _currentIndex,
    onTap: changePage,
    items: <BubbleBottomBarItem>[
      BubbleBottomBarItem(
        backgroundColor: Colors.deepOrangeAccent,
        icon: Icon(CustomIcons.home, color: (theme.getState().then(onValue)) ? Colors.black26 : Colors.white,),
        activeIcon: Icon(CustomIcons.home, color: Colors.white,),
        title: Text("Home", style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12, color: Colors.white)),
      ),
      BubbleBottomBarItem(
        backgroundColor: Colors.blueAccent,
        icon: Icon(CustomIcons.shop, color: Colors.black26,),
        activeIcon: Icon(CustomIcons.shop, color: Colors.white,),
        title: Text("Shop", style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12, color: Colors.white)),
      ),
      BubbleBottomBarItem(
        backgroundColor: Colors.redAccent,
        icon: Icon(CustomIcons.heart, color: Colors.black26,),
        activeIcon: Icon(CustomIcons.heart, color: Colors.white,),
        title: Text("Favorite", style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12, color: Colors.white)),
      ),
      BubbleBottomBarItem(
        backgroundColor: Colors.lightGreen,
        icon: Icon(CustomIcons.user , color: Colors.black26,),
        activeIcon: Icon(CustomIcons.user, color: Colors.white,),
        title: Text("Profile", style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12, color: Colors.white)),
      )
    ],
  ),
);

with the final theme variable i can access getState() method.

// get current value / state of theme for the app : light or dark
Future getState() async {
SharedPreferences prefs = await SharedPreferences.getInstance();

///////// CHANGES HERE
bool val = prefs.getBool('dark_theme_enabled') == null ? false : (prefs.getBool('dark_theme_enabled'));
return val;

}

it just return a boolean from shared preference if the theme is dark or light as of now.

if i try to use it in a if case, i get the error

error: Conditions must have a static type of ‘bool’ as the return type is Future.

what solution can i use ?