I noticed my node was not syncing, and through some debugging on #bitcoin-core-dev it seems like it was caused by running out of disk space which left the node in a desynced state, with the valid chain marked as invalid.

After freeing up some space and doing `reconsiderblock` it fixed it.

Comments from @sipa:

> Ugh. That is bad. Out of disk space should not result in database corruption.

> Database errors propagating up and being interpreted as (permanent) block invalidity was one of the contributing factors to the BDB/LevelDB fork in the 0.7/0.8 transition. 

logs:
```
2022-09-05T00:28:55Z UpdateTip: new best=000000000000000000087e337539b369b19570a88c493725020266387d22dac0 height=752167 version=0x2ce8e004 log2_work=93.70770
7 tx=761139817 date='2022-09-01T15:00:06Z' progress=0.998887 cache=146.8MiB(1101860txo)
2022-09-05T00:28:55Z Fatal LevelDB error: IO error: /home/jb55/.bitcoin/chainstate/2963623.ldb: No space left on device
2022-09-05T00:28:55Z You can use -debug=leveldb to get more complete diagnostic messages
2022-09-05T00:28:55Z *** System error while flushing: Fatal LevelDB error: IO error: /home/jb55/.bitcoin/chainstate/2963623.ldb: No space left on device
2022-09-05T00:28:55Z Error: A fatal internal error occurred, see debug.log for details
2022-09-05T00:28:56Z ERROR: ProcessNewBlock: ActivateBestChain failed (System error while flushing: Fatal LevelDB error: IO error: /home/jb55/.bitcoin/chains
tate/2963623.ldb: No space left on device)
2022-09-05T00:28:56Z ERROR: ConnectBlock: Consensus::CheckTxInputs: 221fa678c5c9953d6cd17e584f05c12ab10ba0f2fc8e8131e266f3f0e9819848, bad-txns-inputs-missing
orspent, CheckTxInputs: inputs missing/spent
2022-09-05T00:28:56Z InvalidChainFound: invalid block=000000000000000000079ba062298aa7cef1888f870c23e303a361c19b097ff8  height=752168  log2_work=93.707719  date=2022-09-01T15:13:42Z
2022-09-05T00:28:56Z InvalidChainFound:  current best=000000000000000000087e337539b369b19570a88c493725020266387d22dac0  height=752167  log2_work=93.707707  date=2022-09-01T15:00:06Z
2022-09-05T00:28:56Z ERROR: ConnectTip: ConnectBlock 000000000000000000079ba062298aa7cef1888f870c23e303a361c19b097ff8 failed, bad-txns-inputs-missingorspent, CheckTxInputs: inputs missing/spent
2022-09-05T00:28:56Z InvalidChainFound: invalid block=000000000000000000079ba062298aa7cef1888f870c23e303a361c19b097ff8  height=752168  log2_work=93.707719  date=2022-09-01T15:13:42Z
2022-09-05T00:28:56Z InvalidChainFound:  current best=000000000000000000087e337539b369b19570a88c493725020266387d22dac0  height=752167  log2_work=93.707707  date=2022-09-01T15:00:06Z
```

uint64_t assumed_chain_bytes{chainparams.AssumedBlockchainSize() * 1024 * 1024 * 1024};
        uint64_t additional_bytes_needed{
            chainman.m_blockman.IsPruneMode() ?
                std::min(chainman.m_blockman.GetPruneTarget(), assumed_chain_bytes) :
                assumed_chain_bytes};
        if (!CheckDiskSpace(args.GetBlocksDirPath(), additional_bytes_needed)) {
            InitWarning(strprintf(_(
                    "Disk space for %s may not accommodate the block files. " \
                    "Approximately %u GB of data will be stored in this directory."
                ),
                fs::quoted(fs::PathToString(args.GetBlocksDirPath())),
                chainparams.AssumedBlockchainSize()
            ));
        }
    }
     Either install a handler to notify us when genesis activates, or set fHaveGenesis directly.
     No locking, as this happens before any background thread is started.
    boost::signals2::connection block_notify_genesis_wait_connection;
    if (WITH_LOCK(chainman.GetMutex(), return chainman.ActiveChain().Tip() == nullptr)) {
        block_notify_genesis_wait_connection = uiInterface.NotifyBlockTip_connect(std::bind(BlockNotifyGenesisWait, std::placeholders::_2));
    } else {
        fHaveGenesis = true;
    }
#if HAVE_SYSTEM
    const std::string block_notify = args.GetArg("-blocknotify", "");
    if (!block_notify.empty()) {
        uiInterface.NotifyBlockTip_connect([block_notify](SynchronizationState sync_state, const CBlockIndex* pBlockIndex) {
            if (sync_state != SynchronizationState::POST_INIT || !pBlockIndex) return;
            std::string command = block_notify;
            ReplaceAll(command, "%s", pBlockIndex->GetBlockHash().GetHex());