`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.
{
public:
    CWallet * const pwallet;
    void ProcessSubScript(const CScript& subscript, UniValue& obj, bool include_addresses = false) const
    {
        
        std::vector<std::vector<unsigned char>> solutions_data;
        txnouttype which_type = Solver(subscript, solutions_data);
        obj.pushKV("script", GetTxnOutputType(which_type));
        obj.pushKV("hex", HexStr(subscript.begin(), subscript.end()));
        CTxDestination embedded;
        UniValue a(UniValue::VARR);
        if (ExtractDestination(subscript, embedded)) {