增加对空白奖励的支持

src/api/controllers/lottery.controller.ts

@@ -35,7 +35,7 @@ class LotteryController extends BaseController {
       let name = '抽奖券'
       let couponUrl = reward.icon
       if (reward.rewardType === 0) {
-        if (!couponMap.has(reward.coupon)) {
+        if (!couponMap.has(reward.coupon) && reward.coupon !== EMPTY) {
           let coupon = await Coupon.findById(reward.coupon)
           couponMap.set(coupon.id, coupon)
         }

src/models/shop/ShopCfg.ts

@@ -51,7 +51,7 @@ export class LotteryCfgClass extends Base {
 
   /**
    * 奖励类型
-   * @type {number} 0: 优惠券, 1: 抽奖券
+   * @type {number} 0: 优惠券, 1: 抽奖券, 9: 留空
    */
   @prop({ default: 0 })
   public rewardType: number