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.
{
    return RPCHelpMan{"waitforblockheight",
                "\nWaits for (at least) block height and returns the height and hash\n"
                "of the current tip.\n"
                "\nReturns the current block on timeout or exit.\n",
                {
                    {"height", RPCArg::Type::NUM, RPCArg::Optional::NO, "Block height to wait for."},
                    {"timeout", RPCArg::Type::NUM, RPCArg::Default{0}, "Time in milliseconds to wait for a response. 0 indicates no timeout."},
                },
                RPCResult{
                    RPCResult::Type::OBJ, "", "",
                    {
                        {RPCResult::Type::STR_HEX, "hash", "The blockhash"},
                        {RPCResult::Type::NUM, "height", "Block height"},
                    }},
                RPCExamples{
                    HelpExampleCli("waitforblockheight", "100 1000")
            + HelpExampleRpc("waitforblockheight", "100, 1000")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    int timeout = 0;
    int height = request.params[0].getInt<int>();
    if (!request.params[1].isNull())
        timeout = request.params[1].getInt<int>();
    CUpdatedBlock block;
    {
        WAIT_LOCK(cs_blockchange, lock);
        if(timeout)