Create a wallet as follows:

```sh
$ bitcoin-cli createwallet "watchonly" true
$ bitcoin-cli -rpcwallet=watchonly getwalletinfo
{
   ...
   "private_keys_enabled": false
}
```

The following should fail, but doesn't:

```sh
$ bitcoin-cli -rpcwallet=watchonly encryptwallet 1234
wallet encrypted; The keypool has been flushed and a new HD seed was generated (if you are using HD). You need to make a new backup.
```

It partially fails silently, because it doesn't actually add a seed. But it does ask for a password when calling `dumpwallet`, which doesn't make sense because we currently don't encrypt anything other than private keys.  
obj.pushKV("immature_balance", ValueFromAmount(bal.m_mine_immature));
    obj.pushKV("txcount",       (int)pwallet->mapWallet.size());
    obj.pushKV("keypoololdest", pwallet->GetOldestKeyPoolTime());
    obj.pushKV("keypoolsize", (int64_t)kpExternalSize);
    CKeyID seed_id = pwallet->GetHDChain().seed_id;
    if (pwallet->CanSupportFeature(FEATURE_HD_SPLIT)) {
        obj.pushKV("keypoolsize_hd_internal",   (int64_t)(pwallet->GetKeyPoolSize() - kpExternalSize));
    }
    if (pwallet->IsCrypted()) {
        obj.pushKV("unlocked_until", pwallet->nRelockTime);
    }
    obj.pushKV("paytxfee", ValueFromAmount(pwallet->m_pay_tx_fee.GetFeePerK()));
    if (!seed_id.IsNull()) {
        obj.pushKV("hdseedid", seed_id.GetHex());
    }
    obj.pushKV("private_keys_enabled", !pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
    if (pwallet->IsScanning()) {
        UniValue scanning(UniValue::VOBJ);
        scanning.pushKV("duration", pwallet->ScanningDuration() / 1000);
        scanning.pushKV("progress", pwallet->ScanningProgress());
        obj.pushKV("scanning", scanning);
    } else {
        obj.pushKV("scanning", false);
    }
    return obj;
}
static UniValue listwalletdir(const JSONRPCRequest& request)
{
    if (request.fHelp || request.params.size() != 0) {
        throw std::runtime_error(