Fixes opensearch-project/opensearch-go#522

[martingrzzler]

Description

Add test for 429 example response. Handle the error with an added sentinel.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.20%. Comparing base (06a6dc8) to head (7f4c2e0).
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #523      +/-   ##
==========================================
+ Coverage   57.29%   66.20%   +8.91%     
==========================================
  Files         315      364      +49     
  Lines        9823     8585    -1238     
==========================================
+ Hits         5628     5684      +56     
+ Misses       2902     1589    -1313     
- Partials     1293     1312      +19     

Flag	Coverage Δ
integration	59.54% <0.00%> (+8.70%)	⬆️
unit	81.64% <100.00%> (+68.79%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
error.go	100.00% <100.00%> (ø)

... and 251 files with indirect coverage changes

[dblock]

Add a line to CHANGELOG please and we're good to go.

[dblock]

Also see #522 (comment)

[dblock]

Looks good. Would be great to have a section in the user guide on error handling.

[dblock]

@martingrzzler You have to sign all your commits with DCO please (git commit -s --amend and force push).