the command "bitcoin-cli getblockstats 0000000000000000000c61ff8f761ce509fc8901d3c22d61fec89637042ea2ba" does not work.

It displays "error: Error parsing JSON:0000000000000000000c61ff8f761ce509fc8901d3c22d61fec89637042ea2ba"

but it should display the block stats like the documentation says.

also bitcoin-cli getblockstats 0 does not work. block number must be at least 1 to work. But blocks start at 0.

tested with 0.20.1 on freebsd, another user on IRC acknowledged the problem.
{
        ser_writedata8(s, DB_BLOCK_HEIGHT);
        ser_writedata32be(s, height);
    }
    template <typename Stream>
    void Unserialize(Stream& s)
    {
        const uint8_t prefix{ser_readdata8(s)};
        if (prefix != DB_BLOCK_HEIGHT) {
            throw std::ios_base::failure("Invalid format for coinstatsindex DB height key");
        }
        height = ser_readdata32be(s);
    }
};
struct DBHashKey {
    uint256 block_hash;
    explicit DBHashKey(const uint256& hash_in) : block_hash(hash_in) {}
    SERIALIZE_METHODS(DBHashKey, obj)
    {
        uint8_t prefix{DB_BLOCK_HASH};
        READWRITE(prefix);
        if (prefix != DB_BLOCK_HASH) {
            throw std::ios_base::failure("Invalid format for coinstatsindex DB hash key");
        }
        READWRITE(obj.block_hash);
    }
};
}; 
std::unique_ptr<CoinStatsIndex> g_coin_stats_index;
CoinStatsIndex::CoinStatsIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory, bool f_wipe)