Subscription error handling

Author: tobias-tengler

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Execution/Nodes/OperationExecutionNode.cs

@@ -209,7 +209,6 @@ private async Task<ExecutionNodeResult> ExecuteInternalAsync(
             Stopwatch.GetElapsedTime(start));
     }
 
-    // TODO: Error handling
     internal async Task<SubscriptionResult> SubscribeAsync(
         OperationPlanContext context,
         CancellationToken cancellationToken = default)
@@ -224,20 +223,26 @@ internal async Task<SubscriptionResult> SubscribeAsync(
         };
 
         var client = context.GetClient(SchemaName, Operation.Operation);
-        var response = await client.ExecuteAsync(context, request, cancellationToken);
 
-        if (!response.IsSuccessful)
+        try
         {
-            return SubscriptionResult.Failed();
+            var response = await client.ExecuteAsync(context, request, cancellationToken);
+
+            var stream = new SubscriptionEnumerable(
+                context,
+                this,
+                response,
+                response.ReadAsResultStreamAsync(cancellationToken),
+                context.GetDiagnosticEvents());
+
+            return SubscriptionResult.Success(stream);
         }
+        catch (Exception exception)
+        {
+            AddErrors(context, exception, variables, ResponseNames);
 
-        var stream = new SubscriptionEnumerable(
-            context,
-            this,
-            response,
-            response.ReadAsResultStreamAsync(cancellationToken),
-            context.GetDiagnosticEvents());
-        return SubscriptionResult.Success(stream);
+            return SubscriptionResult.Failed();
+        }
     }
 
     internal void AddDependency(ExecutionNode node)
@@ -505,7 +510,7 @@ public async ValueTask<bool> MoveNextAsync()
                     _context.AddPartialResults(_node.Source, _resultBuffer, _node.ResponseNames);
                 }
             }
-            catch (Exception ex)
+            catch (Exception exception)
             {
                 // ReSharper disable once ConditionalAccessQualifierIsNonNullableAccordingToAPIContract
                 _resultBuffer[0]?.Dispose();
@@ -516,7 +521,12 @@ public async ValueTask<bool> MoveNextAsync()
                     scope ?? Disposable.Empty,
                     start ?? Stopwatch.GetTimestamp(),
                     Stopwatch.GetTimestamp(),
-                    Exception: ex);
+                    Exception: exception);
+
+                var error = ErrorBuilder.FromException(exception).Build();
+
+                _context.AddErrors(error, _node.ResponseNames, Path.Root);
+
                 return true;
             }
 

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Execution/Results/FetchResultStore.cs

@@ -175,7 +175,7 @@ public void AddErrors(IError error, ReadOnlySpan<string> responseNames, params R
                     continue;
                 }
 
-                _valueCompletion.BuildResult(objectResult, responseNames, error, path);
+                _valueCompletion.BuildErrorResult(objectResult, responseNames, error, path);
 
                 path = ref Unsafe.Add(ref path, 1)!;
             }

src/HotChocolate/Fusion-vnext/src/Fusion.Execution/Execution/Results/ValueCompletion.cs

@@ -2,7 +2,6 @@
 using System.Text.Json;
 using HotChocolate.Fusion.Execution.Clients;
 using HotChocolate.Fusion.Execution.Nodes;
-using HotChocolate.Language;
 using HotChocolate.Types;
 
 namespace HotChocolate.Fusion.Execution;
@@ -47,10 +46,10 @@ public void BuildResult(
         {
             var error = errorTrie?.FindFirstError() ??
                 ErrorBuilder.New()
-                    .SetMessage("Unexpected execution error") // TODO: Better message
+                    .SetMessage("Unexpected Execution Error")
                     .Build();
 
-            BuildResult(objectResult, responseNames, error, objectResult.Path);
+            BuildErrorResult(objectResult, responseNames, error, objectResult.Path);
 
             return;
         }
@@ -80,7 +79,7 @@ public void BuildResult(
         }
     }
 
-    public void BuildResult(
+    public void BuildErrorResult(
         ObjectResult objectResult,
         ReadOnlySpan<string> responseNames,
         IError error,