I'm sometimes getting an invalid json reply from `getwalletinfo` when rescanning is in progress.

The invalid part is this: `"scanning":{"duration":19,"progress":}}` (no value for `progress`).

I can't reliably reproduce this, but I did manage to run into this 3 times now (once every 10-20 attempts or so).

I'm running v0.20.0 and testing against a regtest instance. This happens while doing a batched `importmulti` of 2000 addresses (none of which have history).
if (IsCurrentForAntiFeeSniping(chain, block_hash)) {
        locktime = block_height;
        
        
        
        
        if (GetRandInt(10) == 0)
            locktime = std::max(0, (int)locktime - GetRandInt(100));
    } else {
        
        
        
        locktime = 0;
    }
    assert(locktime < LOCKTIME_THRESHOLD);
    return locktime;
}
OutputType CWallet::TransactionChangeType(const Optional<OutputType>& change_type, const std::vector<CRecipient>& vecSend)