⚡ 优化，公众号菜单编辑增加健壮性判断

pigx-visual/pigx-mp-platform/src/main/java/com/pig4cloud/pigx/mp/handler/MenuHandler.java

@@ -22,6 +22,7 @@ import org.springframework.stereotype.Component;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 /**
  * @author Binary Wang(https://github.com/binarywang)
@@ -58,7 +59,7 @@ public class MenuHandler extends AbstractHandler {
 		List<JSONObject> buttonList = new ArrayList<>();
 		for (JSONObject button : buttons) {
 			JSONArray subButton = button.getJSONArray("sub_button");
-			if (subButton.isEmpty()) {
+			if (Objects.isNull(subButton)) {
 				buttonList.add(button);
 				continue;
 			}