fix: plugin source icon: null error

Author: Akryum

packages/app-frontend/src/features/plugin/PluginSourceIcon.vue

@@ -46,7 +46,10 @@ export default defineComponent({
       @click.stop="go()"
     />
 
-    <template #popper>
+    <template
+      v-if="plugin"
+      #popper
+    >
       <div class="flex space-x-3 items-center">
         <div class="flex items-center justify-center w-8 h-8 bg-gray-700 dark:bg-gray-200 rounded">
           <img