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.
#include <util/check.h>
#include <util/strencodings.h>
#include <util/system.h>
#include <util/translation.h>
#include <validation.h>
#include <validationinterface.h>
#include <versionbits.h>
#include <warnings.h>
#include <stdint.h>
#include <condition_variable>
#include <memory>
#include <mutex>
using kernel::CCoinsStats;
using kernel::CoinStatsHashType;
using node::BlockManager;
using node::NodeContext;
using node::ReadBlockFromDisk;
using node::SnapshotMetadata;
using node::UndoReadFromDisk;
struct CUpdatedBlock
{
    uint256 hash;
    int height;
};
static GlobalMutex cs_blockchange;
static std::condition_variable cond_blockchange;
static CUpdatedBlock latestblock GUARDED_BY(cs_blockchange);
/* Calculate the difficulty for a given block index.
 */
double GetDifficulty(const CBlockIndex* blockindex)