Fixed enum type merging.

src/HotChocolate/Fusion/src/Composition/Pipeline/MergeHandler/EnumTypeMergeHandler.cs

@@ -63,8 +63,8 @@ private static void MergeType(
             // value's deprecation reason
             targetValue.MergeDeprecationWith(sourceValue);
 
-            // Try to apply the source value to the target value
-            context.TryApplySource(sourceValue, sourceSchema, targetValue);
+            // Apply the source value to the target value
+            context.ApplySource(sourceValue, sourceSchema, targetValue);
         }
     }
 }

src/HotChocolate/Fusion/test/Composition.Tests/EnumMergeTests.cs

@@ -0,0 +1,28 @@
+using Xunit.Abstractions;
+
+namespace HotChocolate.Fusion.Composition;
+
+public class EnumMergeTests(ITestOutputHelper output) : CompositionTestBase(output)
+{
+    [Fact]
+    public async Task Output_Enum()
+        => await Succeed(
+            """
+            type Query {
+              field1: Enum1!
+            }
+
+            enum Enum1 {
+              BAR
+            }
+            """,
+            """
+            type Query {
+              field1: Enum1!
+            }
+            
+            enum Enum1 {
+              BAZ
+            }
+            """);
+}

src/HotChocolate/Fusion/test/Composition.Tests/__snapshots__/EnumMergeTests.Output_Enum.graphql

@@ -0,0 +1,19 @@
+schema
+  @fusion(version: 1)
+  @transport(subgraph: "A", location: "https:\/\/localhost:5001\/graphql", kind: "HTTP")
+  @transport(subgraph: "B", location: "https:\/\/localhost:5002\/graphql", kind: "HTTP") {
+  query: Query
+}
+
+type Query {
+  field1: Enum1!
+    @resolver(subgraph: "A", select: "{ field1 }")
+    @resolver(subgraph: "B", select: "{ field1 }")
+}
+
+enum Enum1 {
+  BAR
+    @source(subgraph: "A")
+  BAZ
+    @source(subgraph: "B")
+}