添加缺少参数

pages/orderInfo/orderDetail.vue

@@ -53,7 +53,7 @@
         <view class="info-item info-item--coupon">
           <view class="info-item-label">优惠券</view>
           <view class="info-item-value coupon-value">
-            <text v-if="priceDetail.discountRate != null && priceDetail.discountRate !== ''" class="coupon-amount">{{ priceDetail.discountRate }}折</text>
+            <text v-if="couponDisplayText !== '—'" class="coupon-amount">{{ couponDisplayText }}</text>
             <text v-else class="coupon-placeholder">—</text>
           </view>
         </view>