fix

internal/logic/goods.go

@@ -205,7 +205,13 @@ func MatchGoodsInfo(goods model.ApiGoods, goodsMap GoodsMap) (bomMatching model.
 			//需要用于获取价格的阶梯价
 			if bomMatching.Number < price.Purchases {
 				//ladder = price
-				ladder = goods.LadderPrice[key-1]
+				var index int
+				if key == 0 {
+					index = 0
+				} else {
+					index = key - 1
+				}
+				ladder = goods.LadderPrice[index]
 				break
 			}
 		}