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.
{
    const ArgsManager& args{EnsureAnyArgsman(request.context)};
    ChainstateManager& chainman = EnsureAnyChainman(request.context);
    LOCK(cs_main);
    Chainstate& active_chainstate = chainman.ActiveChainstate();
    const CBlockIndex& tip{*CHECK_NONFATAL(active_chainstate.m_chain.Tip())};
    const int height{tip.nHeight};
    UniValue obj(UniValue::VOBJ);
    obj.pushKV("chain", chainman.GetParams().NetworkIDString());
    obj.pushKV("blocks", height);
    obj.pushKV("headers", chainman.m_best_header ? chainman.m_best_header->nHeight : -1);
    obj.pushKV("bestblockhash", tip.GetBlockHash().GetHex());
    obj.pushKV("difficulty", GetDifficulty(&tip));
    obj.pushKV("time", tip.GetBlockTime());
    obj.pushKV("mediantime", tip.GetMedianTimePast());
    obj.pushKV("verificationprogress", GuessVerificationProgress(chainman.GetParams().TxData(), &tip));
    obj.pushKV("initialblockdownload", active_chainstate.IsInitialBlockDownload());
    obj.pushKV("chainwork", tip.nChainWork.GetHex());
    obj.pushKV("size_on_disk", chainman.m_blockman.CalculateCurrentUsage());
    obj.pushKV("pruned", node::fPruneMode);
    if (node::fPruneMode) {
        obj.pushKV("pruneheight", chainman.m_blockman.GetFirstStoredBlock(tip)->nHeight);
        
        bool automatic_pruning{args.GetIntArg("-prune", 0) != 1};
        obj.pushKV("automatic_pruning",  automatic_pruning);
        if (automatic_pruning) {
            obj.pushKV("prune_target_size",  node::nPruneTarget);
        }
    }
    obj.pushKV("warnings", GetWarnings(false).original);