bugfix: 这bug早有了，可能由于PHP版本更新出来了

app/api/controller/wechat/AuthController.php

@@ -65,6 +65,7 @@ class AuthController
             $unionid = $json2sess['unionid'] ?? '';
             // debuglog("openid=$openId, unionid=$unionid");
             // find by unionid
+            $uid = 0;
             if ($unionid != '') {
                 $uid = WechatUser::where(['unionid' => $unionid])
                     ->where('user_type', 'routine')->value('uid');