https://clickhouse-test-reports.s3.yandex.net/17375/99073c26ee2692f8efe2ab14b2d8ae0fd813b80e/fuzzer/fuzzer.log

```
SELECT
    k,
    topK(v)
FROM 
(
    SELECT
        number % 7 AS k,
        arrayMap(x -> arrayMap(x -> if(x = 0, NULL, toString(x)), range(x)), range(intDiv(number, 1))) AS v
    FROM system.numbers
    LIMIT 257
)
GROUP BY k
ORDER BY k ASC
```
iterator iteratorTo(Cell * ptr)                   { return iterator(this, ptr); }
    const_iterator iteratorToZero() const             { return iteratorTo(this->zeroValue()); }
    iterator iteratorToZero()                         { return iteratorTo(this->zeroValue()); }
    
    
    
    bool ALWAYS_INLINE emplaceIfZero(const Key & x, LookupResult & it, bool & inserted, size_t hash_value)
    {
        
        if (!Cell::need_zero_value_storage)
            return false;
        if (Cell::isZero(x, *this))
        {
            it = this->zeroValue();
            if (!this->hasZero())
            {
                ++m_size;
                this->setHasZero();
                this->zeroValue()->setHash(hash_value);
                inserted = true;
            }
            else
                inserted = false;
            return true;
        }
        return false;
    }
    template <typename KeyHolder>
    void ALWAYS_INLINE emplaceNonZeroImpl(size_t place_value, KeyHolder && key_holder,