ui: improve error

ui/lib/settings/storage.dart

@@ -35,7 +35,7 @@ class _StorageState extends ConsumerState<StorageSettings> {
                     child: const Icon(Icons.add));
               }),
             ),
-        error: (err, trace) => PoError(msg: "网络错误", err: err),
+        error: (err, trace) => PoNetworkError(err: err),
         loading: () => const MyProgressIndicator());
   }