docs: update the related docs about mask= parameter in loc.body()

[jrycw]

Hello team,

This PR updates the documentation related to the mask= parameter in loc.body().

Additionally, it addresses a bug where error messages were not being rendered correctly.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.73%. Comparing base (d71ee99) to head (4293de4).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #589   +/-   ##
=======================================
  Coverage   90.73%   90.73%           
=======================================
  Files          46       46           
  Lines        5416     5416           
=======================================
  Hits         4914     4914           
  Misses        502      502           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[jrycw]

I suggest keeping the mask= experimental callout to address potential edge cases we might not have considered (related issue #588).

[machow]

This LGTM! @jrycw, we added you as a writer to this repo, so you should be able to open PRs from a clone of this repo itself (rather than a fork), and trigger doc build previews. Thanks again for all the incredible work you've done -- however we can make this easier, we're happy to figure out!