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.
{RPCResult::Type::NUM_TIME, "mediantime", "The median block time expressed in " + UNIX_EPOCH_TIME},
                            {RPCResult::Type::NUM, "nonce", "The nonce"},
                            {RPCResult::Type::STR_HEX, "bits", "The bits"},
                            {RPCResult::Type::NUM, "difficulty", "The difficulty"},
                            {RPCResult::Type::STR_HEX, "chainwork", "Expected number of hashes required to produce the current chain"},
                            {RPCResult::Type::NUM, "nTx", "The number of transactions in the block"},
                            {RPCResult::Type::STR_HEX, "previousblockhash", true, "The hash of the previous block (if available)"},
                            {RPCResult::Type::STR_HEX, "nextblockhash", true, "The hash of the next block (if available)"},
                        }},
                    RPCResult{"for verbose=false",
                        RPCResult::Type::STR_HEX, "", "A string that is serialized, hex-encoded data for block 'hash'"},
                },
                RPCExamples{
                    HelpExampleCli("getblockheader", "\"00000000c937983704a73af28acdec37b049d214adbda81d7e2a3dd146f6ed09\"")
            + HelpExampleRpc("getblockheader", "\"00000000c937983704a73af28acdec37b049d214adbda81d7e2a3dd146f6ed09\"")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    uint256 hash(ParseHashV(request.params[0], "hash"));
    bool fVerbose = true;
    if (!request.params[1].isNull())
        fVerbose = request.params[1].get_bool();
    const CBlockIndex* pblockindex;
    const CBlockIndex* tip;
    {
        ChainstateManager& chainman = EnsureAnyChainman(request.context);
        LOCK(cs_main);
        pblockindex = chainman.m_blockman.LookupBlockIndex(hash);
        tip = chainman.ActiveChain().Tip();
    }