update topic avatar.png

pages/topics/goodIdea/cell/index.wxml

@@ -24,7 +24,7 @@
           <view class="detail-userInfo">
             <view class="detail-userInfo-left">
               <view class="detail-user-icon">
-                <image src="{{itemData.topicGroupAvator}}"></image>
+                <image src="{{itemData.topicGroupAvator || '/images/topic/avatar.png'}}"></image>
               </view>
               <view class="detail-userName">{{itemData.topicAuthor}}</view>
               <view class="detail-time">{{itemData.topicGroupCreateTime}}</view>