状态监控增加默认值

src/views/devinfo.vue

@@ -18,11 +18,13 @@
         <div class="box">
           <div class="item">
             <span class="span1">CPU使用率</span>
-            <span>{{ cpudata && cpudata.cpu }}%</span>
+            <span v-if="cpudata && cpudata.cpu">{{ cpudata && cpudata.cpu }}%</span>
+            <span v-else>---</span>
           </div>
           <div class="item">
             <span class="span1">内存使用率</span>
-            <span>{{ memorydata && memorydata.memory }}%</span>
+            <span v-if="memorydata && memorydata.memory">{{ memorydata && memorydata.memory }}%</span>
+            <span v-else>---</span>
           </div>
           <div class="item">
             <span class="span1">VPN连接状态</span>