修复一个unit删除的错误

Unity/Codes/Hotfix/Demo/Unit/M2C_RemoveUnitsHandler.cs

@@ -5,7 +5,11 @@
 	{
 		protected override async ETTask Run(Session session, M2C_RemoveUnits message)
 		{	
-			UnitComponent unitComponent = session.Domain.GetComponent<UnitComponent>();
+			UnitComponent unitComponent = session.DomainScene().CurrentScene()?.GetComponent<UnitComponent>();
+			if (unitComponent == null)
+			{
+				return;
+			}
 			foreach (long unitId in message.Units)
 			{
 				unitComponent.Remove(unitId);