Update CardExecutor.cs

修复func为null时卡死的bug

Game/AI/CardExecutor.cs

@@ -24,7 +24,7 @@ namespace WindBot.Game.AI
 
         public Func<bool?> ConvertToNullableFunc(Func<bool> func)
         {
-            return () => func();
+            return () => func == null || func();
         }
     }
 }
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