Merge #16250: signrawtransactionwithkey: report error when missing redeemScript/witnessScript

0117459 signrawtransactionwithkey: report error when missing redeemScript/witnessScript param (Anthony Towns)

Pull request description:

  Adding support for "witnessScript" as an alternative to "redeemScript" when using "signrawtransactionwithkey" meant that the `RPCTypeCheckObj()` call in `SignTransaction` can't error out just because either parameter is missing -- it's only a problem if both are missing, which isn't a state `RPCTypeCheckObj()` tests for. This results in the regression described in #16249. This patch adds some code to test for this case and give a similar error, namely:

      error code: -8
      error message:
      Missing redeemScript/witnessScript

  Fixes: #16249

ACKs for top commit:
  meshcollider:
    utACK bitcoin/bitcoin@0117459
  promag:
    ACK 0117459. Could also write test without `dict`/`del`:

Tree-SHA512: cf51346b7dea551b7f18f2a93c2a336a293b2535c62c03a5263cd2be8c58cf0cc302891da659c167e88ad1a68a756472c3c07e99f71627c61d32886fc5a3a353

Author: MarcoFalke

src/rpc/rawtransaction_util.cpp

@@ -221,6 +221,9 @@ UniValue SignTransaction(CMutableTransaction& mtx, const UniValue& prevTxsUnival
                     // Automatically also add the P2WSH wrapped version of the script (to deal with P2SH-P2WSH).
                     keystore->AddCScript(GetScriptForWitness(witnessScript));
                 }
+                if (rs.isNull() && ws.isNull()) {
+                    throw JSONRPCError(RPC_INVALID_PARAMETER, "Missing redeemScript/witnessScript");
+                }
             }
         }
     }

test/functional/rpc_createmultisig.py

@@ -129,6 +129,11 @@ def do_multisig(self):
         outval = value - decimal.Decimal("0.00001000")
         rawtx = node2.createrawtransaction([{"txid": txid, "vout": vout}], [{self.final: outval}])
 
+        prevtx_err = dict(prevtxs[0])
+        del prevtx_err["redeemScript"]
+
+        assert_raises_rpc_error(-8, "Missing redeemScript/witnessScript", node2.signrawtransactionwithkey, rawtx, self.priv[0:self.nsigs-1], [prevtx_err])
+
         rawtx2 = node2.signrawtransactionwithkey(rawtx, self.priv[0:self.nsigs - 1], prevtxs)
         rawtx3 = node2.signrawtransactionwithkey(rawtx2["hex"], [self.priv[-1]], prevtxs)