修复字段问题

study/studyGoodsDetail.vue

@@ -328,7 +328,7 @@ export default {
 				if (!this.selectDate) {
 					// 看下个月
 					let dateTime = new Date();
-					dateTime = dateTime.setMonth(d.getMonth() + 1);
+					dateTime = dateTime.setMonth(dateTime.getMonth() + 1);
 					dateTime = new Date(dateTime);
 					this.chnageMonth({
 						year: dateTime.getFullYear(),