Align errors

src/HotChocolate/Core/src/Abstractions/DefaultAsyncEnumerableExecutable.cs

@@ -1,9 +1,8 @@
-using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Threading;
 using System.Threading.Tasks;
+using static HotChocolate.ExecutableErrorHelper;
 
 namespace HotChocolate;
 
@@ -27,7 +26,7 @@ internal sealed class DefaultAsyncEnumerableExecutable<T>(IAsyncEnumerable<T> so
 
             if (await enumerator.MoveNextAsync())
             {
-                throw new InvalidOperationException("Sequence contains more than one element.");
+                throw new GraphQLException(SequenceContainsMoreThanOneElement());
             }
 
             return result;
@@ -48,7 +47,7 @@ public override async ValueTask<List<T>> ToListAsync(CancellationToken cancellat
         return result;
     }
 
-    public async override IAsyncEnumerable<T> ToAsyncEnumerable(
+    public override async IAsyncEnumerable<T> ToAsyncEnumerable(
         [EnumeratorCancellation] CancellationToken cancellationToken = default)
     {
         await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))

src/HotChocolate/Core/src/Abstractions/DefaultQueryableExecutable.cs

@@ -52,7 +52,7 @@ public IQueryableExecutable<T> WithSource(IQueryable<T> src)
     {
         if (source is EnumerableQuery)
         {
-            return new ValueTask<T?>(source.SingleOrDefault());
+            return new ValueTask<T?>(SingleOrDefaultSync(source));
         }
 
         return SingleOrDefaultFromDataSourceAsync(cancellationToken);
@@ -79,12 +79,41 @@ public IQueryableExecutable<T> WithSource(IQueryable<T> src)
         }
 
 #if NET6_0_OR_GREATER
-        return await Task.Run(() => source.SingleOrDefault<T>(), cancellationToken).WaitAsync(cancellationToken);
+        return await Task.Run(() => SingleOrDefaultSync(source), cancellationToken).WaitAsync(cancellationToken);
 #else
-        return await Task.Run(() => source.SingleOrDefault<T>(), cancellationToken);
+        return await Task.Run(() => SingleOrDefaultSync(source), cancellationToken);
 #endif
     }
 
+    private static T? SingleOrDefaultSync(IQueryable<T> query)
+    {
+        var enumerator = query.GetEnumerator();
+
+        try
+        {
+            if (enumerator.MoveNext())
+            {
+                var obj = enumerator.Current;
+
+                if(enumerator.MoveNext())
+                {
+                    throw new GraphQLException(SequenceContainsMoreThanOneElement());
+                }
+
+                return obj;
+            }
+
+            return default;
+        }
+        finally
+        {
+            if(enumerator is IDisposable disposable)
+            {
+                disposable.Dispose();
+            }
+        }
+    }
+
     public override ValueTask<List<T>> ToListAsync(CancellationToken cancellationToken = default)
     {
         if (source is EnumerableQuery)