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.
CCoinsViewCache* coins_view = &active_chainstate.CoinsTip();
    if (fMempool) {
        const CTxMemPool& mempool = EnsureMemPool(node);
        LOCK(mempool.cs);
        CCoinsViewMemPool view(coins_view, mempool);
        if (!view.GetCoin(out, coin) || mempool.isSpent(out)) {
            return UniValue::VNULL;
        }
    } else {
        if (!coins_view->GetCoin(out, coin)) {
            return UniValue::VNULL;
        }
    }
    const CBlockIndex* pindex = active_chainstate.m_blockman.LookupBlockIndex(coins_view->GetBestBlock());
    ret.pushKV("bestblock", pindex->GetBlockHash().GetHex());
    if (coin.nHeight == MEMPOOL_HEIGHT) {
        ret.pushKV("confirmations", 0);
    } else {
        ret.pushKV("confirmations", (int64_t)(pindex->nHeight - coin.nHeight + 1));
    }
    ret.pushKV("value", ValueFromAmount(coin.out.nValue));
    UniValue o(UniValue::VOBJ);
    ScriptToUniv(coin.out.scriptPubKey, o, true, true);
    ret.pushKV("scriptPubKey", o);
    ret.pushKV("coinbase", (bool)coin.fCoinBase);
    return ret;
},
    };
}
static RPCHelpMan verifychain()