[DRAFT] Add a null check for the lower level (de)serializer in ReleaseUnmanagedResources method during dispose flow of C# SerDe objects to avoid NPEs during disposal

native-schema-registry/csharp/AWSGsrSerDe/AWSGsrSerDe.Tests/GlueSchemaRegistrySerDeTests.cs

@@ -191,6 +191,46 @@ public void Exceptions_Are_Thrown_By_DeSerializer()
 //              }
 //          }
 
+        /// <summary>
+        /// Test Serializer disposal when the object is uninitialized but finalizer still runs
+        /// This is not the exact usage scenario but simulates the case when unknown garbage collection race condition
+        /// causes the finalizer to run when the serializer object is null
+        /// </summary>
+        [Test]
+        public void SerializerConstructorDoubleFinalizerTest()
+        {
+            // Create uninitialized object to simulate failed constructor leaving _serializer null
+            var serializer = (GlueSchemaRegistrySerializer)System.Runtime.Serialization.FormatterServices
+                .GetUninitializedObject(typeof(GlueSchemaRegistrySerializer));
+
+            // Manually trigger finalizer on this uninitialized object
+            var finalize = typeof(GlueSchemaRegistrySerializer).GetMethod("Finalize", 
+                System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+            finalize?.Invoke(serializer, null);
+
+            Assert.Pass("Disposal failure handled gracefully");
+        }
+
+        /// <summary>
+        /// Test Deserializer disposal when the object is uninitialized but finalizer still runs
+        /// This is not the exact usage scenario but simulates the case when unknown garbage collection race condition
+        /// causes the finalizer to run when the deserializer object is null
+        /// </summary>
+        [Test]
+        public void DeserializerConstructorDoubleFinalizerTest()
+        {
+            // Create uninitialized object to simulate failed constructor leaving _deserializer null
+            var deserializer = (GlueSchemaRegistryDeserializer)System.Runtime.Serialization.FormatterServices
+                .GetUninitializedObject(typeof(GlueSchemaRegistryDeserializer));
+
+            // Manually trigger finalizer on this uninitialized object
+            var finalize = typeof(GlueSchemaRegistryDeserializer).GetMethod("Finalize", 
+                System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
+            finalize?.Invoke(deserializer, null);
+
+            Assert.Pass("Disposal failure handled gracefully");
+        }
+
         private static GenericRecord GetTestAvroRecord()
         {
             var recordSchema = Schema.Parse(TestAvroSchema);

native-schema-registry/csharp/AWSGsrSerDe/AWSGsrSerDe/GlueSchemaRegistryDeserializer.cs

@@ -144,7 +144,7 @@ private static void Validate(byte[] encoded)
 
         private void ReleaseUnmanagedResources()
         {
-            _deserializer.Dispose();
+            _deserializer?.Dispose();
         }
 
         private void Dispose(bool disposing)

native-schema-registry/csharp/AWSGsrSerDe/AWSGsrSerDe/GlueSchemaRegistrySerializer.cs

@@ -114,7 +114,7 @@ private static void Validate(GlueSchemaRegistrySchema schema, byte[] bytes)
 
         private void ReleaseUnmanagedResources()
         {
-            _serializer.Dispose();
+            _serializer?.Dispose();
         }
 
         private void Dispose(bool disposing)