Fix mouse rotator error spam (#39071)

Ignore mouse rotation requests when the player is switching controlled entity

Content.Shared/MouseRotator/SharedMouseRotatorSystem.cs

@@ -47,6 +47,11 @@ public abstract class SharedMouseRotatorSystem : EntitySystem
 
     private void OnRequestRotation(RequestMouseRotatorRotationEvent msg, EntitySessionEventArgs args)
     {
+        // Ignore the request if the requested entity is not the user's attached entity.
+        // This can happen when a player switches controlled entities while rotating.
+        if (args.SenderSession.AttachedEntity != GetEntity(msg.User))
+            return;
+
         if (args.SenderSession.AttachedEntity is not { } ent
             || !TryComp<MouseRotatorComponent>(ent, out var rotator))
         {