```
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 auto & column = arguments.back().column;
        if (!column)
            throw Exception("Second argument to " + getName() + " must be a constant string describing type."
                " Instead there is non-constant column of type " + arguments.back().type->getName(),
                ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
        const auto * type_col = checkAndGetColumnConst<ColumnString>(column.get());
        if (!type_col)
            throw Exception("Second argument to " + getName() + " must be a constant string describing type."
                " Instead there is a column with the following structure: " + column->dumpStructure(),
                ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
        DataTypePtr type = DataTypeFactory::instance().get(type_col->getValue<String>());
        if constexpr (cast_type == CastType::accurateOrNull)
        {
            return makeNullable(type);
        }
        else
        {
            if (keep_nullable && arguments.front().type->isNullable())
                return makeNullable(type);
            return type;
        }
    }
    bool useDefaultImplementationForNulls() const override { return false; }