Merge #19956: rpc: Improve invalid vout value rpc error message

f471a3b scripted diff: Improve invalid vout value rpc error message (Nima Yazdanmehr)

Pull request description:

  Since the `vout` value can start at `0`, the error message for *negative* values can be improved to something like: `vout cannot be negative`.

ACKs for top commit:
  fanquake:
    ACK f471a3b
  promag:
    Code review ACK f471a3b.

Tree-SHA512: fbdee3d0ddd5b58eb93934a1217b44e125a9ad39e672b1f35c7609c6c5fcf45ae1b731d3d6135b7225d98792dbfc34a50907b8c41274a5b029d7b5c59f886560

src/bitcoin-tx.cpp

@@ -594,7 +594,7 @@ static void MutateTxSign(CMutableTransaction& tx, const std::string& flagStr)
 
             const int nOut = prevOut["vout"].get_int();
             if (nOut < 0)
-                throw std::runtime_error("vout must be positive");
+                throw std::runtime_error("vout cannot be negative");
 
             COutPoint out(txid, nOut);
             std::vector<unsigned char> pkData(ParseHexUV(prevOut["scriptPubKey"], "scriptPubKey"));

src/rpc/rawtransaction_util.cpp

@@ -55,7 +55,7 @@ CMutableTransaction ConstructTransaction(const UniValue& inputs_in, const UniVal
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, missing vout key");
         int nOutput = vout_v.get_int();
         if (nOutput < 0)
-            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout must be positive");
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout cannot be negative");
 
         uint32_t nSequence;
         if (rbf) {
@@ -177,7 +177,7 @@ void ParsePrevouts(const UniValue& prevTxsUnival, FillableSigningProvider* keyst
 
             int nOut = find_value(prevOut, "vout").get_int();
             if (nOut < 0) {
-                throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "vout must be positive");
+                throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "vout cannot be negative");
             }
 
             COutPoint out(txid, nOut);

src/wallet/rpcwallet.cpp

@@ -2204,7 +2204,7 @@ static RPCHelpMan lockunspent()
         const uint256 txid(ParseHashO(o, "txid"));
         const int nOutput = find_value(o, "vout").get_int();
         if (nOutput < 0) {
-            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout must be positive");
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid parameter, vout cannot be negative");
         }
 
         const COutPoint outpt(txid, nOutput);

test/functional/rpc_rawtransaction.py

@@ -96,7 +96,7 @@ def run_test(self):
         assert_raises_rpc_error(-8, "txid must be hexadecimal string (not 'ZZZ7bb8b1697ea987f3b223ba7819250cae33efacb068d23dc24859824a77844')", self.nodes[0].createrawtransaction, [{'txid': 'ZZZ7bb8b1697ea987f3b223ba7819250cae33efacb068d23dc24859824a77844'}], {})
         assert_raises_rpc_error(-8, "Invalid parameter, missing vout key", self.nodes[0].createrawtransaction, [{'txid': txid}], {})
         assert_raises_rpc_error(-8, "Invalid parameter, missing vout key", self.nodes[0].createrawtransaction, [{'txid': txid, 'vout': 'foo'}], {})
-        assert_raises_rpc_error(-8, "Invalid parameter, vout must be positive", self.nodes[0].createrawtransaction, [{'txid': txid, 'vout': -1}], {})
+        assert_raises_rpc_error(-8, "Invalid parameter, vout cannot be negative", self.nodes[0].createrawtransaction, [{'txid': txid, 'vout': -1}], {})
         assert_raises_rpc_error(-8, "Invalid parameter, sequence number is out of range", self.nodes[0].createrawtransaction, [{'txid': txid, 'vout': 0, 'sequence': -1}], {})
 
         # Test `createrawtransaction` invalid `outputs`