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.
COutPoint key;
    Coin coin;
    unsigned int iter{0};
    while (pcursor->Valid()) {
        if (iter % 5000 == 0) node.rpc_interruption_point();
        ++iter;
        if (pcursor->GetKey(key) && pcursor->GetValue(coin)) {
            afile << key;
            afile << coin;
        }
        pcursor->Next();
    }
    afile.fclose();
    UniValue result(UniValue::VOBJ);
    result.pushKV("coins_written", maybe_stats->coins_count);
    result.pushKV("base_hash", tip->GetBlockHash().ToString());
    result.pushKV("base_height", tip->nHeight);
    result.pushKV("path", path.u8string());
    result.pushKV("txoutset_hash", maybe_stats->hashSerialized.ToString());
    
    
    result.pushKV("nchaintx", uint64_t{tip->nChainTx});
    return result;
}
void RegisterBlockchainRPCCommands(CRPCTable& t)
{
    static const CRPCCommand commands[]{
        {"blockchain", &getblockchaininfo},
        {"blockchain", &getchaintxstats},
        {"blockchain", &getblockstats},