`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:
    std::string name;
    std::string purpose;
    CAddressBookData() : purpose("unknown") {}
    typedef std::map<std::string, std::string> StringMap;
    StringMap destdata;
};
struct CRecipient
{
    CScript scriptPubKey;
    CAmount nAmount;
    bool fSubtractFeeFromAmount;
};
typedef std::map<std::string, std::string> mapValue_t;
static inline void ReadOrderPos(int64_t& nOrderPos, mapValue_t& mapValue)