fix: pop out the warning when scanning a undefine product

src/views/ShopPayView.vue

@@ -65,6 +65,7 @@ export default {
     onScanSuccess(decodedText, decodedResult) {
       // handle the scanned code as you like, for example:
       console.log(`Code matched = ${decodedText}`, decodedResult);
+      if (decodedText in this.products){
         var product = this.products[decodedText]
         this.productCar.push({
           'name': product['name'],
@@ -72,6 +73,10 @@ export default {
           'price': product['price'],
           'count': 1
         })
+      } else {
+        this.msg = "商品列表中沒有這項商品："+decodedText
+        this.warningModalStatus = true
+      }
       this.scanner.clear()
     },
     scan() {
@@ -130,7 +135,7 @@ export default {
             </div>
             <div class="block">
               <button class="button is-success is-outlined is-large" @click="scan">掃描商品條碼</button>
-              <div id="reader" width="300px"></div>
+              <div id="reader" width="200px"></div>
             </div>
             <div class="block">
               <table class="table is-fullwidth">