sdss-v mwmVisit data loaders broken

[havok2063]

The SDSS-V data loader for mwmVisit fails to load mwmVisit files that only have BOSS-extension data in them. It loads fine for mwmVisit files with only APOGEE-extension data. I think the issue is during metadata collection, it looks for info specific to certain extensions but not all. e.g. see

specutils/specutils/io/default_loaders/sdss_v.py

Line 589 in 67bea40

meta["date"] = hdulist[hdu].data["date_obs"]

We could either remove the metadata entirely as it's not strictly necessary to load the spectrum, or adjust this code. This is a blocker for sdss/sdss_solara#9

Either I or relevant folks can fix, just creating an issue for tracking.

[havok2063]

@rileythai do you have time to look into this? If not, I can. A relevant id is "54459273". Separately, we also need to add a new loader for the astra aspcap model spectra.

[rileythai]

I have time this weekend -- this should be a simple fix.

[rosteen]

I have time this weekend -- this should be a simple fix.

Great - we just merged another bug fix, I can wait to do a bug fix release until early next week if you can get this done by then. Thanks!

[havok2063]

Thanks @rosteen I'd also like to get #1183 in that fix if possible. If not, I'd like to get it in another release soon after.