fix: username name

template/avater/index.axml

@@ -2,9 +2,7 @@
 <template name="avater">
     <view class="avater">
         <image a:if="{{item.avatar}}" mode="scaleToFill" src="{{item.avatar}}" />
-        <text a:if="{{item.username}}">{{item.username.slice(0, split || 2)}}
-        </text>
-        <text a:else>{{item.name.slice(0, split || 2)}}
+        <text a:else>{{(item.username || item.name).slice(0, split || 2)}}
         </text>
     </view>
 </template>
\ No newline at end of file