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.
if (!pblockindex) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
    }
    if (!fVerbose)
    {
        CDataStream ssBlock(SER_NETWORK, PROTOCOL_VERSION);
        ssBlock << pblockindex->GetBlockHeader();
        std::string strHex = HexStr(ssBlock);
        return strHex;
    }
    return blockheaderToJSON(tip, pblockindex);
},
    };
}
static CBlock GetBlockChecked(BlockManager& blockman, const CBlockIndex* pblockindex) EXCLUSIVE_LOCKS_REQUIRED(::cs_main)
{
    AssertLockHeld(::cs_main);
    CBlock block;
    if (blockman.IsBlockPruned(pblockindex)) {
        throw JSONRPCError(RPC_MISC_ERROR, "Block not available (pruned data)");
    }
    if (!ReadBlockFromDisk(block, pblockindex, Params().GetConsensus())) {
        
        
        
        throw JSONRPCError(RPC_MISC_ERROR, "Block not found on disk");
    }
    return block;
}
static CBlockUndo GetUndoChecked(BlockManager& blockman, const CBlockIndex* pblockindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main)