Flutter app - Problems Lifting State...Suggestions?

Question

I'm working on a Flutter app and trying to make my bottom navigator bar more universal. As part of that, I've moved it to its own file and now need to simply lift state up to the parent class in order to highlight the selected icon. I call it like so from the parent:

bottomNavigationBar: buildBottomNavBar(
  selectedIndex: selectedIndex,
  redrawDisplay: redrawDisplay,
  context: context,
),

And the bottomNaviBar is built like so:

return BottomNavigationBar(
      currentIndex: selectedIndex,
      onTap: (int index) {
        selectedIndex = index;
        redrawDisplay(selectedIndex);
        onBottomMenuTap(index, appProject.picsSelectable, context);
      },
      elevation: 5.0,
      iconSize: 30.0,
      items: <BottomNavigationBarItem>[
        BottomNavigationBarItem(
          icon: Icon(Icons.note_add),
          label: 'Add Metadata',
        ),
        BottomNavigationBarItem(
          icon: Icon(Icons.share),
          label: 'Share Pics',
        ),
        BottomNavigationBarItem(
          icon: Icon(Icons.delete),
          label: 'Delete Pics',
        ),
      ],
    );

The 'redrawDisplay' function is simply a function in the parent class that sets state, like so:

void redrawDisplay({int selectedIndex}) {
  setState(() {
    this.selectedIndex = selectedIndex ?? 0;
  });
}

I swear this was working a few days ago, but now I'm getting the following exception:

════════ Exception caught by gesture ═════════════════════════════════════════════

Closure call with mismatched arguments: function '_SearchScreenState.redrawDisplay'

Receiver: Closure: ({int selectedIndex}) => dynamic from Function 'redrawDisplay':.

Tried calling: _SearchScreenState.redrawDisplay(0)

Found: _SearchScreenState.redrawDisplay({int selectedIndex}) => dynamic

═══════════════════════════════════════════════════════════════════════

Obviously something has changed in my code, but I have been staring at this for hours and haven't cracked it yet. Anybody have some insight into what I've screwed up?

Thanks in advance.