Handling Authentication Errors

HTTP/1.1 401 Unauthorized
WWW-Authenticate: Bearer realm="api",
  error="invalid_token",
  error_description="The access token expired"
Content-Type: application/problem+json

{"type":"...","title":"Unauthorized","status":401}

{
  "type": "https://app.example/problems/auth-failed",
  "title": "Authentication failed",
  "status": 401,
  "code": "auth.invalid_credentials",
  "trace_id": "01HK..."
}

axios.interceptors.response.use(r => r, async (err) => {
  if (err.response?.status === 401 && !err.config._retry) {
    err.config._retry = true;
    await refreshToken();
    return axios(err.config);
  }
  throw err;
});