fix get field on null

app/Services/SuperballActivityService.php

@@ -58,6 +58,12 @@ class SuperballActivityService
             $tierConfigs = $this->getTierConfig();
             $up = null;
             foreach (array_reverse($tierConfigs) as $c) {
+                // 已经是最大的档位，直接升级
+                if ($c['tier'] == self::TIER_MAX
+                    && $c['recharge_required'] < $rechargeToday && $c['turnover_required'] < $turnoverDisplay) {
+                    $up = $c;
+                    break;
+                }
                 if ($c['recharge_required'] < $rechargeToday && $c['turnover_required'] < $turnoverDisplay) {
                     continue;
                 }