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 fs::path temppath = fsbridge::AbsPathJoin(args.GetDataDirNet(), fs::u8path(request.params[0].get_str() + ".incomplete"));
    if (fs::exists(path)) {
        throw JSONRPCError(
            RPC_INVALID_PARAMETER,
            path.u8string() + " already exists. If you are sure this is what you want, "
            "move it out of the way first");
    }
    FILE* file{fsbridge::fopen(temppath, "wb")};
    AutoFile afile{file};
    if (afile.IsNull()) {
        throw JSONRPCError(
            RPC_INVALID_PARAMETER,
            "Couldn't open file " + temppath.u8string() + " for writing.");
    }
    NodeContext& node = EnsureAnyNodeContext(request.context);
    UniValue result = CreateUTXOSnapshot(
        node, node.chainman->ActiveChainstate(), afile, path, temppath);
    fs::rename(temppath, path);
    result.pushKV("path", path.u8string());
    return result;
},
    };
}
UniValue CreateUTXOSnapshot(
    NodeContext& node,
    Chainstate& chainstate,
    AutoFile& afile,
    const fs::path& path,
    const fs::path& temppath)
{