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 (IsValidDestination(dest)) {
        entry.pushKV("address", EncodeDestination(dest));
    }
}
/**
 * List transactions based on the given criteria.
 *
 * @param  pwallet        The wallet.
 * @param  wtx            The wallet transaction.
 * @param  nMinDepth      The minimum confirmation depth.
 * @param  fLong          Whether to include the JSON version of the transaction.
 * @param  ret            The UniValue into which the result is stored.
 * @param  filter_ismine  The "is mine" filter flags.
 * @param  filter_label   Optional label string to filter incoming transactions.
 */
static void ListTransactions(interfaces::Chain::Lock& locked_chain, CWallet* const pwallet, const CWalletTx& wtx, int nMinDepth, bool fLong, UniValue& ret, const isminefilter& filter_ismine, const std::string* filter_label) EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)
{
    CAmount nFee;
    std::list<COutputEntry> listReceived;
    std::list<COutputEntry> listSent;
    wtx.GetAmounts(listReceived, listSent, nFee, filter_ismine);
    bool involvesWatchonly = wtx.IsFromMe(ISMINE_WATCH_ONLY);
    
    if (!filter_label)
    {
        for (const COutputEntry& s : listSent)
        {