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.  
if (IsMine(*pwallet, dest)) {
        pwallet->SetAddressBook(dest, label, "receive");
    } else {
        pwallet->SetAddressBook(dest, label, "send");
    }
    return NullUniValue;
}
static CTransactionRef SendMoney(interfaces::Chain::Lock& locked_chain, CWallet * const pwallet, const CTxDestination &address, CAmount nValue, bool fSubtractFeeFromAmount, const CCoinControl& coin_control, mapValue_t mapValue)
{
    CAmount curBalance = pwallet->GetBalance().m_mine_trusted;
    
    if (nValue <= 0)
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid amount");
    if (nValue > curBalance)
        throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, "Insufficient funds");
    if (pwallet->GetBroadcastTransactions() && !pwallet->chain().p2pEnabled()) {
        throw JSONRPCError(RPC_CLIENT_P2P_DISABLED, "Error: Peer-to-peer functionality missing or disabled");
    }
    
    CScript scriptPubKey = GetScriptForDestination(address);
    
    CReserveKey reservekey(pwallet);
    CAmount nFeeRequired;
    std::string strError;
    std::vector<CRecipient> vecSend;
    int nChangePosRet = -1;
    CRecipient recipient = {scriptPubKey, nValue, fSubtractFeeFromAmount};
    vecSend.push_back(recipient);
    CTransactionRef tx;
    if (!pwallet->CreateTransaction(locked_chain, vecSend, tx, reservekey, nFeeRequired, nChangePosRet, strError, coin_control)) {