> 
> Warning: Operand of null-aware operation '??' has type 'int' which excludes null. \_countries.indexWhere((country)
> 
> 
> 

```
onTap: () {
    int index =
        _countries.indexWhere((country) {
              return country.startsWith(
                  alphabet.toUpperCase());
            }) ??
            0;
    _listController.jumpTo(
      index * 60.0,
    );
  },
  child: Text(
    alphabet,
    style: TextStyle(
      color: _theme.primaryColor,
      fontSize: 14.0,
      fontWeight: FontWeight.bold,
    ),
  ),

```