is there a 'invisible' constant like key-word in flutter?

i’m new and was lurking around with listview when i cameacross ‘OnTap’ function but when i implement i get the error "Invalid constant value" I have to everytime click on QuickFix any solution for this? i’ve attached the image and the code for the Widget

image of code snippet

class navDrawer extends StatelessWidget {
  const navDrawer({
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Column(children: <Widget>[
        Expanded(
          child: ListView(padding: EdgeInsets.zero, children: <Widget>[
            const DrawerHeader(
              decoration: BoxDecoration(
                color: Colors.amber,
              ),
              child: const Text(
                'Labels',
                style: TextStyle(fontSize: 50, color: Colors.black),
              ),
            ),
            ListTile(
              selectedColor: Colors.deepOrange,
              selected: true,
              focusColor: Colors.deepOrange,
              leading: const Icon(Icons.label_important_outline),
              title: const Text(
                'Temporary',
                style: TextStyle(fontSize: 30, color: Colors.blueGrey),
              ),
              onTap: () {
                //made it work by quickfix
                print('Temporary');
              },
            ),
            const ListTile(
              selectedColor: Colors.lightBlue,
              leading: Icon(Icons.label_important),
              title: const Text(
                'Important',
                style: TextStyle(fontSize: 30, color: Colors.blueGrey),
              ),
              focusColor: Colors.cyan,
              onTap:(){
                //the one in the image
              },
            ),
            const ListTile(
              leading: Icon(Icons.label_important),
              title: const Text(
                'Health',
                style: TextStyle(fontSize: 30, color: Colors.blueGrey),
              ),
              focusColor: Colors.cyan,
            ),
            const ListTile(
              leading: Icon(Icons.label_important),
              title: const Text(
                'Personal',
                style: TextStyle(fontSize: 30, color: Colors.blueGrey),
              ),
              focusColor: Colors.cyan,
            )
          ]),
        ),
      ]),
    );
  }
}

i tried to understand the problem and hoping for a solution.