fix: 修复空字串set

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

src/main/java/cn/citycraft/LuckLottery/config/PlayerData.java

@@ -43,7 +43,9 @@ public class PlayerData {
     public static void clearLottery() {
         for (final Entry<String, List<List<String>>> pl : playerLottery.entrySet()) {
             final String p = pl.getKey();
-            playerdata.set(p, null);
+            if (p != null && !"".equals(p)) {
+                playerdata.set(p, null);
+            }
         }
         playerLottery.clear();
         playerdata.save();