Fix broken build on .NET SDK v10.0.200

Author: bkoelman

src/JsonApiDotNetCore/AtomicOperations/Processors/DeleteProcessor.cs

@@ -24,7 +24,10 @@ public DeleteProcessor(IDeleteService<TResource, TId> service)
         ArgumentNullException.ThrowIfNull(operation);
 
         var id = (TId)operation.Resource.GetTypedId();
-        await _service.DeleteAsync(id!, cancellationToken);
+#pragma warning disable CS8607 // A possible null value may not be used for a type marked with [NotNull] or [DisallowNull]
+        // Justification: Temporary workaround for R# bug at https://youtrack.jetbrains.com/issue/RSRP-503026.
+        await _service.DeleteAsync(id, cancellationToken);
+#pragma warning restore CS8607 // A possible null value may not be used for a type marked with [NotNull] or [DisallowNull]
 
         return null;
     }

src/JsonApiDotNetCore/Diagnostics/CodeTimingSessionManager.cs

@@ -89,10 +89,7 @@ private static void AssertNoActiveSession()
 
     private static void SessionOnDisposed(object? sender, EventArgs args)
     {
-        if (_session != null)
-        {
-            _session.Disposed -= SessionOnDisposed;
-            _session = null;
-        }
+        _session?.Disposed -= SessionOnDisposed;
+        _session = null;
     }
 }