`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.
#include <wallet/wallet.h>
#include <memory>
#include <set>
#include <stdint.h>
#include <utility>
#include <vector>
#include <consensus/validation.h>
#include <interfaces/chain.h>
#include <rpc/server.h>
#include <test/test_bitcoin.h>
#include <validation.h>
#include <wallet/coincontrol.h>
#include <wallet/test/wallet_test_fixture.h>
#include <boost/test/unit_test.hpp>
#include <univalue.h>
extern UniValue importmulti(const JSONRPCRequest& request);
extern UniValue dumpwallet(const JSONRPCRequest& request);
extern UniValue importwallet(const JSONRPCRequest& request);
BOOST_FIXTURE_TEST_SUITE(wallet_tests, WalletTestingSetup)
static void AddKey(CWallet& wallet, const CKey& key)