test(amber): add unit tests for ErrorUtils

[Yicong-Huang]

What changes were proposed in this PR?

Adds scalatest coverage for amber/src/main/scala/org/apache/texera/amber/error/ErrorUtils.scala. The module had no dedicated spec.

Any related issues, documentation, discussions?

Closes #4708.

How was this PR tested?

sbt scalafmtCheckAll
sbt "WorkflowExecutionService/testOnly org.apache.texera.amber.error.ErrorUtilsSpec"

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (claude-opus-4-7)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 41.88%. Comparing base (8cf5b9a) to head (80c669e).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4709      +/-   ##
============================================
- Coverage     42.85%   41.88%   -0.97%     
- Complexity     2027     2035       +8     
============================================
  Files           957      978      +21     
  Lines         34077    34569     +492     
  Branches       3753     3779      +26     
============================================
- Hits          14604    14480     -124     
- Misses        18692    19314     +622     
+ Partials        781      775       -6     

Flag	Coverage Δ
access-control-service	?
amber	40.97% <ø> (+0.21%)	⬆️
computing-unit-managing-service	?
config-service	?
file-service	?
python	84.15% <ø> (+0.02%)	⬆️
workflow-compiling-service	?

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[Copilot]

Pull request overview

This PR adds a dedicated ScalaTest spec for ErrorUtils, improving unit-test coverage for Amber's shared error-handling helpers. It fits into the Amber backend by validating the formatting, wrapping, and reconstruction behavior used when surfacing runtime failures across worker/controller boundaries.

Changes:

• Add a new ErrorUtilsSpec covering safely, mkConsoleMessage, and mkControlError.
• Add reconstruction/formatting tests for reconstructThrowable and getStackTraceWithAllCauses.
• Add worker-ID parsing tests for getOperatorFromActorIdOpt, including empty and fallback cases.

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