Handle 204 (No Content) result from /charon/getDataset
Handle 204 (No Content) result from /charon/getDataset

These are to be returned by the server to indicate that the
dataset wasn't valid, but that we shouldn't show the 404 page.
We instead show the splash page, which will list the datasets
returned by the getAvailable request

nextstrain/auspice,nextstrain/auspice,nextstrain/auspice