Fix network error message for resource server

src/App.vue

@@ -40,7 +40,11 @@ async function get_resource(id: string) {
   ).catch(
     err => {
       resource.value = []
-      msg.value = `${err.message} (${err.response.statusText}): ${err.response.data["detail"]}`
+      if (err.response) {
+        msg.value = `${err.message} (${err.response.statusText}): ${err.response.data["detail"]}`
+      } else {
+        msg.value = `${err.message} (cannot reach the resource server)`
+      }
     }
   )
 }