workFlowIframe修改src错误

src/components/classRoomHelper/component/workFlowIframe.vue

@@ -22,7 +22,7 @@ export default {
             handler: function(newVal, oldVal) {
                 if (newVal) {
                     this.checkIndex = 0
-                    this.src = newVal[this.checkIndex].src ? newVal[this.checkIndex].src : ''
+                    this.src = (newVal && newVal.length && newVal[this.checkIndex].src) ? newVal[this.checkIndex].src : ''
                     console.log('-------------------',this.src);
                     this.$forceUpdate();
                 }