sentrycore: wrap error with log message

[bobheadxi]

Right now, error messages are super non-descript because most context is in the log message, not in the error message. I think it's useful to have the log message here because it also matters where each error is being reported from, so grouping by log messages is something we probably want.

And of course we add the scope, because we want those to become important keys in navigating observability reports.

[codecov-commenter]

Codecov Report

Merging #2 (f747bb5) into main (4de9057) will increase coverage by 0.56%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main       #2      +/-   ##
==========================================
+ Coverage   56.63%   57.19%   +0.56%     
==========================================
  Files          13       13              
  Lines         535      542       +7     
==========================================
+ Hits          303      310       +7     
  Misses        222      222              
  Partials       10       10              

Impacted Files	Coverage Δ
internal/sinkcores/sentrycore/worker.go	80.43% <100.00%> (+1.61%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4de9057...f747bb5. Read the comment docs.

[jhchabran]

Good call!