refactor: migrate demo applications to playground (#4116)

* chore: detail adjustment

* refactor: Migrate demo applications to playground

* perf: logic optimization

* chore: update docs

* chore: update docs

docs/src/guide/essentials/server.md

@@ -221,7 +221,7 @@ function createRequestClient(baseURL: string) {
     if (status >= 200 && status < 400 && code === 0) {
       return data;
     }
-    throw new Error(msg);
+    throw new Error(`Error ${status}: ${msg}`);
   });
   return client;
 }