fix: 修复不存在Tag的报错

Signed-off-by: 502647092 <admin@yumc.pw>

src/main/java/pw/yumc/YumCore/update/SubscribeTask.java

@@ -283,6 +283,8 @@ public class SubscribeTask implements Runnable, Listener {
             String result = def;
             try {
                 result = document.getElementsByTagName(tag).item(0).getTextContent();
+            } catch (NullPointerException ignored) {
+                Log.d("当前插件不存在标签 %s 使用默认值 %s !", tag, def);
             } catch (Exception e) {
                 Log.d(e);
             }