```
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
FormatSettings format_settings;
            for (size_t i = 0; i < size; ++i)
            {
                ReadBufferFromMemory read_buffer(&chars[current_offset], offsets[i] - current_offset - 1);
                data_type_to.deserializeAsWholeText(column_to, read_buffer, format_settings);
                if (!read_buffer.eof())
                    throwExceptionForIncompletelyParsedValue(read_buffer, result_type);
                current_offset = offsets[i];
            }
            return res;
        }
        else
            throw Exception("Illegal column " + arguments[0].column->getName()
                    + " of first argument of conversion function from string",
                ErrorCodes::ILLEGAL_COLUMN);
    }
};
template <>
struct ConvertImpl<DataTypeString, DataTypeUInt32, NameToUnixTimestamp, ConvertDefaultBehaviorTag>
    : ConvertImpl<DataTypeString, DataTypeDateTime, NameToUnixTimestamp, ConvertDefaultBehaviorTag> {};
template <>
struct ConvertImpl<DataTypeString, DataTypeUInt32, NameToUnixTimestamp, ConvertReturnNullOnErrorTag>
    : ConvertImpl<DataTypeString, DataTypeDateTime, NameToUnixTimestamp, ConvertReturnNullOnErrorTag> {};
/** If types are identical, just take reference to column.
  */
template <typename T, typename Name>
struct ConvertImpl<std::enable_if_t<!T::is_parametric, T>, T, Name, ConvertDefaultBehaviorTag>
{
    template <typename Additions = void *>
    static ColumnPtr execute(const ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t ,