优化第一阶梯起始值校验

src/views/ecw/productPrice/components/PriceStep.vue

@@ -102,7 +102,7 @@ export default {
       const index = this.index
       const errors = []
       // 区间设置检查
-      if(index > 0 && !this.value.startNum){
+      if(typeof this.value.startNum != "number"){
         errors.push(this.$t("请设置{priceName}第{index}阶段的起始值", {
             index: index + 1,
             priceName: this.priceName