fix stderr output for handle tests

[nicklan]

What changes are proposed in this pull request?

New rustc has slightly different error messages.

How was this change tested?

tests pass

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.48%. Comparing base (cbb52a4) to head (ef64793).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #630      +/-   ##
==========================================
- Coverage   83.50%   83.48%   -0.02%     
==========================================
  Files          74       74              
  Lines       16919    16915       -4     
  Branches    16919    16915       -4     
==========================================
- Hits        14128    14122       -6     
- Misses       2133     2139       +6     
+ Partials      658      654       -4     

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