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.
FlushStateMode mode,
        int nManualPruneHeight = 0);
    
    void ForceFlushStateToDisk();
    
    
    void PruneAndFlush();
    /**
     * Find the best known block, and make it the tip of the block chain. The
     * result is either failure or an activated best chain. pblock is either
     * nullptr or a pointer to a block that is already loaded (to avoid loading
     * it again from disk).
     *
     * ActivateBestChain is split into steps (see ActivateBestChainStep) so that
     * we avoid holding cs_main for an extended period of time; the length of this
     * call may be quite long during reindexing or a substantial reorg.
     *
     * May not be called with cs_main held. May not be called in a
     * validationinterface callback.
     *
     * @returns true unless a system error occurred
     */
    bool ActivateBestChain(
        BlockValidationState& state,
        std::shared_ptr<const CBlock> pblock = nullptr)
        EXCLUSIVE_LOCKS_REQUIRED(!m_chainstate_mutex)
        LOCKS_EXCLUDED(::cs_main);
    bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, BlockValidationState& state, CBlockIndex** ppindex, bool fRequested, const FlatFilePos* dbp, bool* fNewBlock, bool min_pow_checked) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    
    DisconnectResult DisconnectBlock(const CBlock& block, const CBlockIndex* pindex, CCoinsViewCache& view)