I think that if a reorg fails due to an error while disconnecting blocks, the node should shut down.

My thought is that if we are trying to switch to a more work chain and something goes wrong before we can even try to validate that more-work chain, then we have a problem that is not related to the chain we're trying to switch to but instead related to our own hardware or software; shutting down and having the user deal with the issue is better than continuing on, when we know there's a more work chain that we're unable to try validating.

This has recently come up on testnet, where unpatched nodes are unable to reorg from the invalid chain containing the duplicate-input-in-a-transaction block, but rather than crash or shutdown they are continuing on the invalid chain, with messages like this in the debug log:

```
ERROR: DisconnectTip(): DisconnectBlock 00000000210004840364b52bc5e455d888f164e4264a4fec06a514b67e9d5722 failed
```
CBlock block;
            if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
                return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
            if (!g_chainstate.ConnectBlock(block, state, pindex, coins, chainparams))
                return error("VerifyDB(): *** found unconnectable block at %d, hash=%s (%s)", pindex->nHeight, pindex->GetBlockHash().ToString(), FormatStateMessage(state));
        }
    }
    LogPrintf("[DONE].\n");
    LogPrintf("No coin database inconsistencies in last %i blocks (%i transactions)\n", block_count, nGoodTransactions);
    return true;
}
bool CChainState::RollforwardBlock(const CBlockIndex* pindex, CCoinsViewCache& inputs, const CChainParams& params)
{
    
    CBlock block;
    if (!ReadBlockFromDisk(block, pindex, params.GetConsensus())) {
        return error("ReplayBlock(): ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
    }
    for (const CTransactionRef& tx : block.vtx) {
        if (!tx->IsCoinBase()) {
            for (const CTxIn &txin : tx->vin) {
                inputs.SpendCoin(txin.prevout);
            }
        }
        
        AddCoins(inputs, *tx, pindex->nHeight, true);
    }
    return true;
}
bool CChainState::ReplayBlocks(const CChainParams& params, CCoinsView* view)