`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.
{
    LOCK(cs_wallet);
    if (!memonly && !WalletBatch(*database).WriteHDChain(chain))
        throw std::runtime_error(std::string(__func__) + ": writing chain failed");
    hdChain = chain;
}
bool CWallet::IsHDEnabled() const
{
    return !hdChain.seed_id.IsNull();
}
void CWallet::SetWalletFlag(uint64_t flags)
{
    LOCK(cs_wallet);
    m_wallet_flags |= flags;
    if (!WalletBatch(*database).WriteWalletFlags(m_wallet_flags))
        throw std::runtime_error(std::string(__func__) + ": writing wallet flags failed");
}
bool CWallet::IsWalletFlagSet(uint64_t flag)
{
    return (m_wallet_flags & flag);
}
bool CWallet::SetWalletFlags(uint64_t overwriteFlags, bool memonly)