`ScanForWalletTransactions()` has the following comment about its return value:

```
 * Returns null if scan was successful. Otherwise, if a complete rescan was not
 * possible (due to pruning or corruption), returns pointer to the most recent
 * block that could not be scanned.
```

This is not strictly true. If `abortrescan` is called, then `ScanForWalletTransactions()` will return `nullptr`, even though the scan wasn't successful to the tip.

This in turn causes a minor bug in `importmulti`, where the call doesn't return the correct error and warning about potentially not finding transactions if `abortrescan` was called.

I think the correct fix is for `ScanForWalletTransactions()` to inform the caller that the rescan was aborted.
{
    AssertLockHeld(cs_wallet); 
    DBErrors nZapSelectTxRet = WalletBatch(*database,"cr+").ZapSelectTx(vHashIn, vHashOut);
    for (uint256 hash : vHashOut) {
        const auto& it = mapWallet.find(hash);
        wtxOrdered.erase(it->second.m_it_wtxOrdered);
        mapWallet.erase(it);
    }
    if (nZapSelectTxRet == DBErrors::NEED_REWRITE)
    {
        if (database->Rewrite("\x04pool"))
        {
            setInternalKeyPool.clear();
            setExternalKeyPool.clear();
            m_pool_key_to_index.clear();
            
            
            
        }
    }
    if (nZapSelectTxRet != DBErrors::LOAD_OK)
        return nZapSelectTxRet;
    MarkDirty();
    return DBErrors::LOAD_OK;
}
DBErrors CWallet::ZapWalletTx(std::vector<CWalletTx>& vWtx)