```
SELECT
    CAST(([2, 1, 1023], ['', '']), 'Map(UInt8, String)') AS map,
    map[10]
```

Triggers `Assertion 'n < size()' failed` in `DB::ColumnString::operator[](unsigned long)`
https://clickhouse-test-reports.s3.yandex.net/18481/64c4ade5b0e0c9a13d6c2475431daf431fc97554/fuzzer/fuzzer.log

Introduced here: #17829
First found here: #18481
{
        
        if (checkAndGetDataType<DataTypeString>(from_type_untyped.get()))
        {
            return [] (ColumnsWithTypeAndName & arguments, const DataTypePtr & result_type, const ColumnNullable *, size_t )
            {
                return ConvertImplGenericFromString::execute(arguments, result_type);
            };
        }
        DataTypePtr from_nested_type;
        DataTypePtr to_nested_type;
        const auto * from_type = checkAndGetDataType<DataTypeArray>(from_type_untyped.get());
        
        if (from_type && to_type)
        {