<!-- 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.
throw std::runtime_error(
            "abandontransaction \"txid\"\n"
            "\nMark in-wallet transaction <txid> as abandoned\n"
            "This will mark this transaction and all its in-wallet descendants as abandoned which will allow\n"
            "for their inputs to be respent.  It can be used to replace \"stuck\" or evicted transactions.\n"
            "It only works on transactions which are not included in a block and are not currently in the mempool.\n"
            "It has no effect on transactions which are already abandoned.\n"
            "\nArguments:\n"
            "1. \"txid\"    (string, required) The transaction id\n"
            "\nResult:\n"
            "\nExamples:\n"
            + HelpExampleCli("abandontransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\"")
            + HelpExampleRpc("abandontransaction", "\"1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d\"")
        );
    }
    
    
    pwallet->BlockUntilSyncedToCurrentChain();
    LOCK2(cs_main, pwallet->cs_wallet);
    uint256 hash;
    hash.SetHex(request.params[0].get_str());
    if (!pwallet->mapWallet.count(hash)) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid or non-wallet transaction id");
    }
    if (!pwallet->AbandonTransaction(hash)) {
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not eligible for abandonment");
    }
    return NullUniValue;
}
static UniValue backupwallet(const JSONRPCRequest& request)