Fix slog errors

[rafaelroquetto]

A few tests contained wrong slog statements that led to errors such as

 slog.Logger.Error arg "err" should be a string or a slog.Attr (possible missing key or value)  

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.16%. Comparing base (f632c99) to head (8c4d065).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1104      +/-   ##
==========================================
- Coverage   73.50%   73.16%   -0.34%     
==========================================
  Files         172      172              
  Lines       13091    13091              
==========================================
- Hits         9622     9578      -44     
- Misses       2920     2968      +48     
+ Partials      549      545       -4     

Flag	Coverage Δ
integration-test	50.79% <ø> (-0.24%)	⬇️
k8s-integration-test	52.92% <ø> (+0.05%)	⬆️
oats-test	33.52% <ø> (-0.21%)	⬇️
unittests	45.68% <ø> (ø)

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[grcevski]

LGTM! Awesome, thanks for fixing it.

[mariomac]

Good job! To put in context, the experimental API of the slog library required that the second argument of the Error method was an actual error. We updated the library when it was made part of Go, but we forgot to update some invocations.

Thanks for fixing!

[mariomac]

Merging to unblock other failing PRs.