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{"getdifficulty",
                "\nReturns the proof-of-work difficulty as a multiple of the minimum difficulty.\n",
                {},
                RPCResult{
                    RPCResult::Type::NUM, "", "the proof-of-work difficulty as a multiple of the minimum difficulty."},
                RPCExamples{
                    HelpExampleCli("getdifficulty", "")
            + HelpExampleRpc("getdifficulty", "")
                },
        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
{
    ChainstateManager& chainman = EnsureAnyChainman(request.context);
    LOCK(cs_main);
    return GetDifficulty(chainman.ActiveChain().Tip());
},
    };
}
static RPCHelpMan getblockfrompeer()