How to remove leading from Flutter Search delegate?

Question

I'm building a search screen with SearchDelegate in Flutter. But cannot remove the leading from it. I tried to return null for buildLeading(), but it still takes space for leading. if there is any other way to achieve the same UI functionality, please recommend me. how can I remove leading? My flutter version is Flutter 3.7.5.

searchDelegate code:

class CustomSearch extends SearchDelegate<String> {
  List<String> searchTerms = [
    "Apple",
    "Banana",
    "Mango",
    "Pear",
    "Watermelons",
    "Blueberries",
    "Pineapples",
    "Strawberries"
  ];

  @override
  ThemeData appBarTheme(BuildContext context) {
    return ThemeData(
      textTheme: TextTheme(
        titleLarge: AppStyles.gilroySemiBold16BlueGray600,
      ),
      appBarTheme: const AppBarTheme(
        iconTheme: IconThemeData(weight: 0.1),
        backgroundColor: AppColors.blue100,
        elevation: 0,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.vertical(
            bottom: Radius.circular(16),
          ),
        ),
      ),
      inputDecorationTheme: AppStyles.inputDecorationTheme(context),
    );
  }

  @override
  List<Widget>? buildActions(BuildContext context) {
    return [];
  }

  @override
  Widget? buildLeading(BuildContext context) {
    return null;
  }

// third overwrite to show query result
  @override
  Widget buildResults(BuildContext context) {
    List<String> matchQuery = [];
    for (var fruit in searchTerms) {
      if (fruit.toLowerCase().contains(query.toLowerCase())) {
        matchQuery.add(fruit);
      }
    }
    return ListView.builder(
      itemCount: matchQuery.length,
      itemBuilder: (context, index) {
        var result = matchQuery[index];
        return ListTile(
          title: Text(result),
        );
      },
    );
  }

  @override
  Widget buildSuggestions(BuildContext context) {
    List<String> matchQuery = [];
    for (var fruit in searchTerms) {
      if (fruit.toLowerCase().contains(query.toLowerCase())) {
        matchQuery.add(fruit);
      }
    }
    return ListView.builder(
      itemCount: matchQuery.length,
      itemBuilder: (context, index) {
        var result = matchQuery[index];
        return ListTile(
          title: Text(result),
        );
      },
    );
  }
}