```
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
{
        const char * function_name = name;
        return [function_name] (
            ColumnsWithTypeAndName & arguments, const DataTypePtr & res_type, const ColumnNullable * nullable_col, size_t )
        {
            const auto & first_col = arguments.front().column.get();
            const auto & result_type = typeid_cast<const EnumType &>(*res_type);
            const ColumnStringType * col = typeid_cast<const ColumnStringType *>(first_col);
            if (col && nullable_col && nullable_col->size() != col->size())
                throw Exception("ColumnNullable is not compatible with original", ErrorCodes::LOGICAL_ERROR);
            if (col)
            {
                const auto size = col->size();
                auto res = result_type.createColumn();
                auto & out_data = static_cast<typename EnumType::ColumnType &>(*res).getData();
                out_data.resize(size);
                if (nullable_col)
                {
                    for (const auto i : ext::range(0, size))
                    {
                        if (!nullable_col->isNullAt(i))
                            out_data[i] = result_type.getValue(col->getDataAt(i));
                    }