Add more error handling

src/main/java/org/example/HelloPlugin/CheckinCommand.java

@@ -71,6 +71,8 @@ public class CheckinCommand implements CommandExecutor {
                     double reward = getReward(streak);
                     econ.depositPlayer(player, reward);
                     player.sendMessage("§a签到成功！已连续签到§b" + streak + "§a天，获得§c$" + reward + "§c奖励");
+                } else {
+                    player.sendMessage("§c未知错误。");
                 }
             } catch (SQLException e) {
                 plugin.getLogger().severe(e.getMessage());