Handle exceptions in ParallelRpcClient.GetFirstSuccessAsync

Previously, if one RPC node threw an exception (e.g. ConnectTimeout),
GetFirstSuccessAsync would propagate it immediately, ignoring results
from other nodes still in flight. This could cause lost transaction
results when broadcasting to multiple nodes.

Now exceptions from individual tasks are caught and treated as errors,
allowing the method to continue waiting for remaining nodes. User-
initiated cancellation via CancellationToken still propagates normally.

Author: matsakiv

Revelium.Evm.Tests/Rpc/ParallelRpcTests.cs

@@ -53,6 +53,17 @@ private static void SetupNetworkError(Mock<HttpMessageHandler> handler, string u
             .ThrowsAsync(new HttpRequestException("Network error"));
     }
 
+    private static void SetupTimeout(Mock<HttpMessageHandler> handler, string url)
+    {
+        handler
+            .Protected()
+            .Setup<Task<HttpResponseMessage>>(
+                "SendAsync",
+                ItExpr.Is<HttpRequestMessage>(req => req.RequestUri!.ToString() == url),
+                ItExpr.IsAny<CancellationToken>())
+            .ThrowsAsync(new TaskCanceledException("Connect timeout"));
+    }
+
     private static void SetupRpcError(Mock<HttpMessageHandler> handler, string url, int errorCode, string errorMessage)
     {
         var response = new
@@ -490,4 +501,67 @@ await Assert.ThrowsAsync<InvalidOperationException>(async () =>
             await parallelClient.GetBalanceAsync(ADDRESS);
         });
     }
+
+    [Fact]
+    public async Task Test_ParallelRpcClient_FirstClientTimeout_SecondSucceeds()
+    {
+        // Arrange
+        var handler1 = new Mock<HttpMessageHandler>();
+        var handler2 = new Mock<HttpMessageHandler>();
+        SetupTimeout(handler1, RPC_URL_1);
+        SetupJsonRpcResponseResult(handler2, RPC_URL_2, "0xb9052a11d665600");
+
+        var client1 = CreateRpcClient(RPC_URL_1, handler1);
+        var client2 = CreateRpcClient(RPC_URL_2, handler2);
+        var parallelClient = new ParallelRpcClient([client1, client2], []);
+
+        // Act
+        var (balance, error) = await parallelClient.GetBalanceAsync(ADDRESS);
+
+        // Assert
+        Assert.Null(error);
+        Assert.Equal(833256783000000000, balance);
+    }
+
+    [Fact]
+    public async Task Test_ParallelRpcClient_AllClientsTimeout_ReturnsError()
+    {
+        // Arrange
+        var handler1 = new Mock<HttpMessageHandler>();
+        var handler2 = new Mock<HttpMessageHandler>();
+        SetupTimeout(handler1, RPC_URL_1);
+        SetupTimeout(handler2, RPC_URL_2);
+
+        var client1 = CreateRpcClient(RPC_URL_1, handler1);
+        var client2 = CreateRpcClient(RPC_URL_2, handler2);
+        var parallelClient = new ParallelRpcClient([client1, client2], []);
+
+        // Act
+        var (_, error) = await parallelClient.GetBalanceAsync(ADDRESS);
+
+        // Assert
+        Assert.NotNull(error);
+        Assert.Equal(RpcClient.HTTP_REQUEST_ERROR, error.Code);
+    }
+
+    [Fact]
+    public async Task Test_ParallelRpcClient_SendRawTransaction_BroadcastTimeout_SecondSucceeds()
+    {
+        // Arrange
+        var broadcastHandler1 = new Mock<HttpMessageHandler>();
+        var broadcastHandler2 = new Mock<HttpMessageHandler>();
+        SetupTimeout(broadcastHandler1, BROADCAST_URL_1);
+        SetupJsonRpcResponseResult(broadcastHandler2, BROADCAST_URL_2, "0x1234567890abcdef");
+
+        var broadcastClient1 = CreateRpcClient(BROADCAST_URL_1, broadcastHandler1);
+        var broadcastClient2 = CreateRpcClient(BROADCAST_URL_2, broadcastHandler2);
+        var parallelClient = new ParallelRpcClient([], [broadcastClient1, broadcastClient2]);
+
+        // Act
+        var (txHash, error) = await parallelClient.SendRawTransactionAsync("0xabcdef123456");
+
+        // Assert
+        Assert.Null(error);
+        Assert.Equal("0x1234567890abcdef", txHash);
+    }
 }

Revelium.Evm/Revelium.Evm.csproj

@@ -16,7 +16,7 @@
     <RepositoryUrl>https://github.com/matsakiv/Revelium.Evm</RepositoryUrl>
 
     <Authors>mativ</Authors>
-    <Version>0.0.24</Version>
+    <Version>0.0.25</Version>
     <Description>Revelium.Evm is .NET integration library for EVM-compatible networks</Description>
     <Copyright>Copyright © Igor Matsak</Copyright>
     <Title>Revelium.Evm</Title>

Revelium.Evm/Rpc/ParallelRpcClient.cs

@@ -53,14 +53,21 @@ private async Task<Result<TValue>> GetFirstSuccessAsync<TValue>(
                 break;
 
             var completedTask = await Task.WhenAny(remainingTasks);
-
-            var (result, error) = await completedTask;
             completedTasks.Add(completedTask);
 
-            if (error == null)
-                return result;
+            try
+            {
+                var (result, error) = await completedTask;
+
+                if (error == null)
+                    return result;
 
-            lastError = error;
+                lastError = error;
+            }
+            catch (Exception) when (!cancellationToken.IsCancellationRequested)
+            {
+                lastError = new Error(RpcClient.HTTP_REQUEST_ERROR, "Request failed");
+            }
         }
 
         // All tasks completed with errors, return the last error
@@ -97,14 +104,21 @@ private async Task<NullableResult<TValue>> GetFirstSuccessAsync<TValue>(
                 break;
 
             var completedTask = await Task.WhenAny(remainingTasks);
-
-            var (result, error) = await completedTask;
             completedTasks.Add(completedTask);
 
-            if (error == null)
-                return result;
+            try
+            {
+                var (result, error) = await completedTask;
+
+                if (error == null)
+                    return result;
 
-            lastError = error;
+                lastError = error;
+            }
+            catch (Exception) when (!cancellationToken.IsCancellationRequested)
+            {
+                lastError = new Error(RpcClient.HTTP_REQUEST_ERROR, "Request failed");
+            }
         }
 
         // All tasks completed with errors, return the last error