fix observer ghost spawn error (#35253)

Content.Server/GameTicking/GameTicker.Spawning.cs

@@ -359,6 +359,7 @@ namespace Content.Server.GameTicking
             if (DummyTicker)
                 return;
 
+            var makeObserver = false;
             Entity<MindComponent?>? mind = player.GetMind();
             if (mind == null)
             {
@@ -366,10 +367,13 @@ namespace Content.Server.GameTicking
                 var (mindId, mindComp) = _mind.CreateMind(player.UserId, name);
                 mind = (mindId, mindComp);
                 _mind.SetUserId(mind.Value, player.UserId);
-                _roles.MindAddRole(mind.Value, "MindRoleObserver");
+                makeObserver = true;
             }
 
             var ghost = _ghost.SpawnGhost(mind.Value);
+            if (makeObserver)
+                _roles.MindAddRole(mind.Value, "MindRoleObserver");
+
             _adminLogger.Add(LogType.LateJoin,
                 LogImpact.Low,
                 $"{player.Name} late joined the round as an Observer with {ToPrettyString(ghost):entity}.");