Fix `fabric:get_db_info/1`
Fix `fabric:get_db_info/1`

We weren't properly removing shards that had an error as well as
returning errors to functions that don't expect them.

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb