<!-- 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.
if (it != pwallet->mapKeyMetadata.end()) {
            meta = &it->second;
        }
    }
    if (!meta) {
        auto it = pwallet->m_script_metadata.find(CScriptID(scriptPubKey));
        if (it != pwallet->m_script_metadata.end()) {
            meta = &it->second;
        }
    }
    if (meta) {
        ret.pushKV("timestamp", meta->nCreateTime);
        if (!meta->hdKeypath.empty()) {
            ret.pushKV("hdkeypath", meta->hdKeypath);
            ret.pushKV("hdseedid", meta->hd_seed_id.GetHex());
            ret.pushKV("hdmasterkeyid", meta->hd_seed_id.GetHex());
        }
    }
    
    
    
    UniValue labels(UniValue::VARR);
    std::map<CTxDestination, CAddressBookData>::iterator mi = pwallet->mapAddressBook.find(dest);
    if (mi != pwallet->mapAddressBook.end()) {
        labels.push_back(AddressBookDataToJSON(mi->second, true));
    }
    ret.pushKV("labels", std::move(labels));
    return ret;
}
static UniValue getaddressesbylabel(const JSONRPCRequest& request)