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.
{
    CHECK_NONFATAL(blockindex);
    int nShift = (blockindex->nBits >> 24) & 0xff;
    double dDiff =
        (double)0x0000ffff / (double)(blockindex->nBits & 0x00ffffff);
    while (nShift < 29)
    {
        dDiff *= 256.0;
        nShift++;
    }
    while (nShift > 29)
    {
        dDiff /= 256.0;
        nShift--;
    }
    return dDiff;
}
static int ComputeNextBlockAndDepth(const CBlockIndex* tip, const CBlockIndex* blockindex, const CBlockIndex*& next)
{
    next = tip->GetAncestor(blockindex->nHeight + 1);
    if (next && next->pprev == blockindex) {
        return tip->nHeight - blockindex->nHeight + 1;
    }
    next = nullptr;
    return blockindex == tip ? 1 : -1;
}
static const CBlockIndex* ParseHashOrHeight(const UniValue& param, ChainstateManager& chainman)