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 (change_type) {
        return *change_type;
    }
    
    
    if (m_default_address_type == OutputType::LEGACY) {
        return OutputType::LEGACY;
    }
    
    
    for (const auto& recipient : vecSend) {
        
        int witnessversion = 0;
        std::vector<unsigned char> witnessprogram;
        if (recipient.scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
            return OutputType::BECH32;
        }
    }
    
    return m_default_address_type;
}
bool CWallet::CreateTransactionInternal(