```
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
else
            {
                bool parsed;
                if constexpr (parsing_mode == ConvertFromStringParsingMode::BestEffort)
                {
                    if constexpr (to_datetime64)
                    {
                        DateTime64 res = 0;
                        parsed = tryParseDateTime64BestEffort(res, vec_to.getScale(), read_buffer, *local_time_zone, *utc_time_zone);
                        vec_to[i] = res;
                    }
                    else
                    {
                        time_t res;
                        parsed = tryParseDateTimeBestEffort(res, read_buffer, *local_time_zone, *utc_time_zone);
                        vec_to[i] = res;
                    }
                }
                else
                {
                    if constexpr (to_datetime64)
                    {
                        DateTime64 value = 0;
                        parsed = tryReadDateTime64Text(value, vec_to.getScale(), read_buffer, *local_time_zone);
                        vec_to[i] = value;
                    }
                    else if constexpr (IsDataTypeDecimal<ToDataType>)
                        parsed = ToDataType::tryReadText(vec_to[i], read_buffer, ToDataType::maxPrecision(), vec_to.getScale());
                    else
                        parsed = tryParseImpl<ToDataType>(vec_to[i], read_buffer, local_time_zone);