修复Icon缺失报错的问题

sub-government-affairs-service/src/layouts/component/Menu/Icon.vue

@@ -1,12 +1,13 @@
 <template>
-  <el-icon v-if="icon.includes('icon')" :class="`iconfont ${icon}`" :size="size" />
+  <el-icon v-if="!icon" :size="size" />
+  <el-icon v-else-if="icon.includes('icon')" :class="`iconfont ${icon}`" :size="size" />
   <el-icon v-else :size="size"> <component :is="icon" /></el-icon>
 </template>
 <script setup name="layout-icon">
 defineProps({
   icon: {
     type: String,
-    required: true,
+    default: '',
   },
   size: {
     type: Number,