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.
{
    AssertLockHeld(::cs_main);
    CBlockUndo blockUndo;
    if (blockman.IsBlockPruned(pblockindex)) {
        throw JSONRPCError(RPC_MISC_ERROR, "Undo data not available (pruned data)");
    }
    if (!UndoReadFromDisk(blockUndo, pblockindex)) {
        throw JSONRPCError(RPC_MISC_ERROR, "Can't read undo data from disk");
    }
    return blockUndo;
}
const RPCResult getblock_vin{
    RPCResult::Type::ARR, "vin", "",
    {
        {RPCResult::Type::OBJ, "", "",
        {
            {RPCResult::Type::ELISION, "", "The same output as verbosity = 2"},
            {RPCResult::Type::OBJ, "prevout", "(Only if undo information is available)",
            {
                {RPCResult::Type::BOOL, "generated", "Coinbase or not"},
                {RPCResult::Type::NUM, "height", "The height of the prevout"},
                {RPCResult::Type::STR_AMOUNT, "value", "The value in " + CURRENCY_UNIT},
                {RPCResult::Type::OBJ, "scriptPubKey", "",
                {
                    {RPCResult::Type::STR, "asm", "Disassembly of the public key script"},
                    {RPCResult::Type::STR, "desc", "Inferred descriptor for the output"},