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.  
{
    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
    CWallet* const pwallet = wallet.get();
    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
        return NullUniValue;
    }
    if (request.fHelp || (request.params.size() > 3 ))
        throw std::runtime_error(
            RPCHelpMan{"getbalance",
                "\nReturns the total available balance.\n"
                "The available balance is what the wallet considers currently spendable, and is\n"
                "thus affected by options which limit spendability such as -spendzeroconfchange.\n",
                {
                    {"dummy", RPCArg::Type::STR, RPCArg::Optional::OMITTED_NAMED_ARG, "Remains for backward compatibility. Must be excluded or set to \"*\"."},
                    {"minconf", RPCArg::Type::NUM,  "0", "Only include transactions confirmed at least this many times."},
                    {"include_watchonly", RPCArg::Type::BOOL,  "false", "Also include balance in watch-only addresses (see 'importaddress')"},
                },
                RPCResult{
            "amount              (numeric) The total amount in " + CURRENCY_UNIT + " received for this wallet.\n"
                },