`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.
{
    if (hashUnset())
        return 0;
    AssertLockHeld(cs_main);
    
    CBlockIndex* pindex = LookupBlockIndex(hashBlock);
    if (!pindex || !chainActive.Contains(pindex))
        return 0;
    return ((nIndex == -1) ? (-1) : 1) * (chainActive.Height() - pindex->nHeight + 1);
}
int CMerkleTx::GetBlocksToMaturity(interfaces::Chain::Lock& locked_chain) const
{
    if (!IsCoinBase())
        return 0;
    int chain_depth = GetDepthInMainChain(locked_chain);
    assert(chain_depth >= 0); 
    return std::max(0, (COINBASE_MATURITY+1) - chain_depth);
}
bool CMerkleTx::IsImmatureCoinBase(interfaces::Chain::Lock& locked_chain) const
{
    
    return GetBlocksToMaturity(locked_chain) > 0;
}
bool CWalletTx::AcceptToMemoryPool(interfaces::Chain::Lock& locked_chain, const CAmount& nAbsurdFee, CValidationState& state)