fix: 修复边框选不上的问题

frontend/src/views/background/BackgroundItem.vue

@@ -29,7 +29,7 @@ export default {
   },
   computed: {
     itemActive() {
-      return this.curComponent.commonBackground && this.curComponent.commonBackground.innerImage === this.template.url
+      return this.curComponent && this.curComponent.commonBackground && this.curComponent.commonBackground.innerImage === this.template.url
     },
     classBackground() {
       if (this.template.url) {

frontend/src/views/background/index.vue

@@ -102,7 +102,7 @@ export default {
     }
   },
   mounted() {
-    if (this.curComponent.commonBackground && this.curComponent.commonBackground.outerImage && typeof (this.curComponent.commonBackground.outerImage) === 'string') {
+    if (this.curComponent && this.curComponent.commonBackground && this.curComponent.commonBackground.outerImage && typeof (this.curComponent.commonBackground.outerImage) === 'string') {
       this.fileList.push({ url: this.curComponent.commonBackground.outerImage })
     }
     this.backgroundOrigin = deepCopy(this.curComponent.commonBackground)