`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:
    const CWalletTx *tx;
    int i;
    int nDepth;
    
    int nInputBytes;
    
    bool fSpendable;
    
    bool fSolvable;
    
    bool use_max_sig;
    /**
     * Whether this output is considered safe to spend. Unconfirmed transactions
     * from outside keys and unconfirmed replacement transactions are considered
     * unsafe and will not be used to fund new spending transactions.
     */
    bool fSafe;
    COutput(const CWalletTx *txIn, int iIn, int nDepthIn, bool fSpendableIn, bool fSolvableIn, bool fSafeIn, bool use_max_sig_in = false)