rpc fix streaming trace methods returning result:null in case of error

.github/workflows/scripts/rpc_version.env

@@ -1,2 +1,2 @@
-RPC_VERSION=v2.16.0
+RPC_VERSION=v2.17.0
 

rpc/jsonrpc/debug_api_test.go

@@ -210,6 +210,48 @@ func TestTraceTransactionNotFound(t *testing.T) {
 	require.ErrorContains(t, err, "transaction not found")
 }
 
+// TestTraceErrorPathsWriteNoStream verifies that streaming trace methods write nothing to the
+// stream on early error paths. This is required for JSON-RPC 2.0 compliance: the handler omits
+// the "result" field when the stream is untouched, producing {error:...} without result:null.
+func TestTraceErrorPathsWriteNoStream(t *testing.T) {
+	m, _, _ := rpcdaemontest.CreateTestExecModule(t)
+	api := NewPrivateDebugAPI(newBaseApiForTest(m), m.DB, nil, 0, false)
+
+	newStream := func() (*bytes.Buffer, jsonstream.Stream) {
+		var buf bytes.Buffer
+		return &buf, jsonstream.New(jsoniter.NewStream(jsoniter.ConfigDefault, &buf, 4096))
+	}
+
+	t.Run("TraceBlockByNumber_genesis", func(t *testing.T) {
+		buf, s := newStream()
+		err := api.TraceBlockByNumber(m.Ctx, rpc.BlockNumber(0), &tracersConfig.TraceConfig{}, s)
+		require.ErrorContains(t, err, "genesis is not traceable")
+		require.NoError(t, s.Flush())
+		require.Empty(t, buf.Bytes(), "stream must be empty on early error")
+	})
+
+	t.Run("TraceBlockByHash_genesis", func(t *testing.T) {
+		var genesisHash common.Hash
+		require.NoError(t, m.DB.View(m.Ctx, func(tx kv.Tx) error {
+			genesisHash, _, _ = m.BlockReader.CanonicalHash(m.Ctx, tx, 0)
+			return nil
+		}))
+		buf, s := newStream()
+		err := api.TraceBlockByHash(m.Ctx, genesisHash, &tracersConfig.TraceConfig{}, s)
+		require.ErrorContains(t, err, "genesis is not traceable")
+		require.NoError(t, s.Flush())
+		require.Empty(t, buf.Bytes(), "stream must be empty on early error")
+	})
+
+	t.Run("TraceTransaction_genesis", func(t *testing.T) {
+		buf, s := newStream()
+		err := api.TraceTransaction(m.Ctx, common.HexToHash("0xdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef"), &tracersConfig.TraceConfig{}, s)
+		require.ErrorContains(t, err, "transaction not found")
+		require.NoError(t, s.Flush())
+		require.Empty(t, buf.Bytes(), "stream must be empty on early error")
+	})
+}
+
 func TestTraceTransactionNoRefund(t *testing.T) {
 	m, _, _ := rpcdaemontest.CreateTestExecModule(t)
 	api := NewPrivateDebugAPI(newBaseApiForTest(m), m.DB, nil, 0, false)

rpc/jsonrpc/tracing.go

@@ -67,12 +67,10 @@ func (api *DebugAPIImpl) traceBlock(ctx context.Context, blockNrOrHash rpc.Block
 	}
 
 	if (blockNrOrHash.BlockHash == nil && hash == common.Hash{}) {
-		stream.WriteNil()
 		return fmt.Errorf("block #%d not found", *blockNrOrHash.BlockNumber)
 	}
 
 	if blockNumber == 0 {
-		stream.WriteNil()
 		return fmt.Errorf("genesis is not traceable")
 	}
 
@@ -88,7 +86,6 @@ func (api *DebugAPIImpl) traceBlock(ctx context.Context, blockNrOrHash rpc.Block
 		return err
 	}
 	if block == nil {
-		stream.WriteNil()
 		return fmt.Errorf("invalid arguments; block with hash %x not found", hash)
 	}
 
@@ -290,7 +287,6 @@ func (api *DebugAPIImpl) TraceTransaction(ctx context.Context, hash common.Hash,
 	}
 
 	if blockNum == 0 {
-		stream.WriteNil()
 		return fmt.Errorf("genesis is not traceable")
 	}
 
@@ -319,12 +315,10 @@ func (api *DebugAPIImpl) TraceTransaction(ctx context.Context, hash common.Hash,
 			return err
 		}
 		if txNumMin+1 > txNum {
-			stream.WriteNil()
 			return fmt.Errorf("uint underflow txnums error txNum: %d, txNumMin: %d, blockNum: %d", txNum, txNumMin, blockNum)
 		}
 		txnIndex = int(txNum - txNumMin - 1)
 		if txnIndex >= block.Transactions().Len() {
-			stream.WriteNil()
 			return fmt.Errorf("transaction %#x not found", hash)
 		}
 	}
@@ -511,7 +505,6 @@ func (api *DebugAPIImpl) TraceCallMany(ctx context.Context, bundles []Bundle, si
 		return err
 	}
 	if len(bundles) == 0 {
-		stream.WriteNil()
 		return errors.New("empty bundles")
 	}
 	empty := true
@@ -522,7 +515,6 @@ func (api *DebugAPIImpl) TraceCallMany(ctx context.Context, bundles []Bundle, si
 	}
 
 	if empty {
-		stream.WriteNil()
 		return errors.New("empty bundles")
 	}
 
@@ -544,7 +536,6 @@ func (api *DebugAPIImpl) TraceCallMany(ctx context.Context, bundles []Bundle, si
 		return err
 	}
 	if header == nil {
-		stream.WriteNil()
 		return fmt.Errorf("block %d(%x) not found", blockNum, hash)
 	}