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).
}
        else {
            error = strprintf(_("Error loading %s"), walletFile);
            return nullptr;
        }
    }
    if (fFirstRun)
    {
        
        walletInstance->SetMinVersion(FEATURE_LATEST);
        walletInstance->AddWalletFlags(wallet_creation_flags);
        
        if (!walletInstance->IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS)) {
            walletInstance->SetupLegacyScriptPubKeyMan();
        }
        if (!(wallet_creation_flags & (WALLET_FLAG_DISABLE_PRIVATE_KEYS | WALLET_FLAG_BLANK_WALLET))) {
            LOCK(walletInstance->cs_wallet);
            if (walletInstance->IsWalletFlagSet(WALLET_FLAG_DESCRIPTORS)) {
                walletInstance->SetupDescriptorScriptPubKeyMans();
                
            } else {
                
                for (auto spk_man : walletInstance->GetActiveScriptPubKeyMans()) {
                    if (!spk_man->SetupGeneration()) {
                        error = _("Unable to generate initial keys");
                        return nullptr;
                    }
                }
            }
        }