Missing .zgroups in Spraggins preview?

[mccalluc]

Loading https://portal.stage.hubmapconsortium.org/preview/multimodal-molecular-imaging-data, I get a number of 404s for .zgroup files. The UI functionality seems fine, but is there a way we can get rid of the 404s? (Either put stub files at those URLS, or understand why they are being requested, and change what we're doing on the client side?) cc @ilan-gold .

https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.ims.zarr/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/0/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/1/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/2/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/3/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/4/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/5/.zgroup
https://vitessce-data.storage.googleapis.com/0.0.27/master_release/spraggins/spraggins.mxif.zarr/6/.zgroup

[manzt]

This is from Zarr.js (and something I've been meaning to get around to): https://github.com/gzuidhof/zarr.js/blob/375ce0c299469a970da6bb5653513564e25806bb/src/creation.ts#L154

The zarr.openArray checks if node is a group before trying to open it as an array (these are mutually exclusive nodes). This checks for the <path>/.zgroup key in the store, which in our case is an HTTPStore that uses fetch internally to ping the server.

It's really annoying and an artifact of how zarr-python opens an array conservatively. I've been meaning to get around to fixing it but haven't had the time.