`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.
if (fPruneMode) {
        auto locked_chain = pwallet->chain().lock();
        CBlockIndex *block = pindexStop ? pindexStop : pChainTip;
        while (block && block->nHeight >= pindexStart->nHeight) {
            if (!(block->nStatus & BLOCK_HAVE_DATA)) {
                throw JSONRPCError(RPC_MISC_ERROR, "Can't rescan beyond pruned data. Use RPC call getblockchaininfo to determine your pruned height.");
            }
            block = block->pprev;
        }
    }
    const CBlockIndex* stopBlock;
    CWallet::ScanResult result =
        pwallet->ScanForWalletTransactions(pindexStart, pindexStop, reserver, stopBlock, true);
    switch (result) {
    case CWallet::ScanResult::SUCCESS:
        stopBlock = pindexStop ? pindexStop : pChainTip;
        break;
    case CWallet::ScanResult::FAILURE:
        throw JSONRPCError(RPC_MISC_ERROR, "Rescan failed. Potentially corrupted data files.");
    case CWallet::ScanResult::USER_ABORT:
        throw JSONRPCError(RPC_MISC_ERROR, "Rescan aborted.");
        
    }
    UniValue response(UniValue::VOBJ);
    response.pushKV("start_height", pindexStart->nHeight);
    response.pushKV("stop_height", stopBlock->nHeight);
    return response;
}
class DescribeWalletAddressVisitor : public boost::static_visitor<UniValue>