<!-- Describe the issue -->

When trying to sign a transaction in a encrypted wallet that is locked, version 0.16 would return the following error:

```"Please enter the wallet passphrase with walletpassphrase first."```

While doing exactly the same procedure against 0.17, the response is something like:

```json
"hex": "020000000183ac9cc1137c444f32356fb070ecba194c87a05e43674c06a55f5b1d0561eabc0000000000ffffffff0180626a94000000001600141875aa6ab19c2551c11759cf3e9f4dd7aa40bcf500000000",
       "complete": false,
       "errors": [
         {
           "txid": "bcea61051d5b5fa5064c67435ea0874c19baec70b06f35324f447c13c19cac83",
           "vout": 0,
           "witness": [
           ],
           "scriptSig": "",
           "sequence": 4294967295,
           "error": "Unable to sign input, invalid stack size (possibly missing key)"
         }
     ]

```

<!--- What behavior did you expect? -->

v0.17 should check if the wallet is locked before trying to sign the tx and return the same error as v0.16 for consistency reasons.
std::shuffle(vecSend.begin(), vecSend.end(), FastRandomContext());
    
    CReserveKey keyChange(pwallet);
    CAmount nFeeRequired = 0;
    int nChangePosRet = -1;
    std::string strFailReason;
    CTransactionRef tx;
    bool fCreated = pwallet->CreateTransaction(vecSend, tx, keyChange, nFeeRequired, nChangePosRet, strFailReason, coin_control);
    if (!fCreated)
        throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, strFailReason);
    CValidationState state;
    if (!pwallet->CommitTransaction(tx, std::move(mapValue), {} , keyChange, g_connman.get(), state)) {
        strFailReason = strprintf("Transaction commit failed:: %s", FormatStateMessage(state));
        throw JSONRPCError(RPC_WALLET_ERROR, strFailReason);
    }
    return tx->GetHash().GetHex();
}
static UniValue addmultisigaddress(const JSONRPCRequest& request)
{
    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() < 2 || request.params.size() > 4) {
        std::string msg = "addmultisigaddress nrequired [\"key\",...] ( \"label\" \"address_type\" )\n"
            "\nAdd a nrequired-to-sign multisignature address to the wallet. Requires a new wallet backup.\n"
            "Each key is a Bitcoin address or hex-encoded public key.\n"
            "This functionality is only intended for use with non-watchonly addresses.\n"
            "See `importaddress` for watchonly p2sh address support.\n"