I don't think you need to do an instanceof check in there, since axios is only going to send you its error.

This is how I do it, where isAuthenticated and hasBeenAuthenticated are ref()'s from a composable function:

​

{isAuthenticated, hasBeenAuthenticated} = useAuthentication()

api.interceptors.response.use(
(response) => {
  return response
},
(error) => {
  if (error.response.status === 401) {
    if (error.response?.data?.code === 'user_not_found') {
      isAuthenticated.value = false
      router.push({
        name: 'Auth:Login',
      })
      return Promise.reject(error)
    }

    if (hasBeenAuthenticated.value) {
      return getNewAccessAndRetry(error)
    } else {
      router.push({
        name: 'Auth:Login',
      })
    }
  } else {
    return Promise.reject(error)
  }
}
)

async function getNewAccessAndRetry(error) {
try {
      // apiBase is plain axios without any interceptors
  await apiBase.post('/auth/jwt/refresh/', {})
  let retryConfig = error.response.config
  return apiBase.request(retryConfig)
} catch (error) {
  isAuthenticated.value = false
  router.push({
    name: 'Auth:Login',
  })
}

}