Cleanup usage of unwrap() in re_data_store

[Artxiom]

What

Part of #6330
Removes or explicitly allows unwrap() where it makes sense.

Checklist

• I have read and agree to Contributor Guide and the Code of Conduct
• I've included a screenshot or gif (if applicable)
• I have tested the web demo (if applicable):
  • Using examples from latest main build: rerun.io/viewer
  • Using full set of examples from nightly build: rerun.io/viewer
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG
• If applicable, add a new check to the release checklist!

• PR Build Summary
• Recent benchmark results
• Wasm size tracking

To run all checks from main, comment on the PR with @rerun-bot full-check.

[emilk]

thanks!

[Artxiom]

@emilk As I don't have write access - how do you guys handle usually external contributions? Do I need to check the other boxes or do anything else, or will you take over from here?

[emilk]

Our CI for external contributors is slightly broken: #1994

The checkboxes you have control over though

[Artxiom]

Haha, okay.

I just meant what are the guideline for the checkboxes? The first two are obvious but when is it necessary to e.g. test the web demos or when to add something to the checklist, what's a good PR title, etc? And I can't change the labels anyway.
So should I always just leave the remaining checkboxes unchecked or just check them all?

And thanks!