[Dashboard] when an API request fails, the dashboard should show the error message, e.g., the cluster or jobs page

Currently, if any API request fails on the cluster or job page, it will show no active clusters or no active jobs without any error message, which is confusing.

When there are actually clusters but it's failed to fetch, people should know that it's not because all their clusters/jobs are gone but just the API server has some failures during fetching that information.