修改显示问题

src/mobile_preview/index.vue

@@ -439,6 +439,7 @@ export default {
   .audit-content {
     display: flex;
     width: 100%;
+    height: calc(100vh - 56px);
   }
 }
 </style>

src/views/book/courseware/preview/components/common/PreviewMixin.js

@@ -52,6 +52,7 @@ const mixin = {
     content: {
       handler(newVal) {
         if (this.type === 'edit') return;
+        if (!newVal) return;
         this.data = JSON.parse(newVal);
       },
       immediate: true,