fix #4215: More informative error messages when package construction fails

[drernie]

Description

Ensure we return sufficient information on errors to enable efficient debugging.

TODO

• Unit tests
• Changelog entry (skip if change is not significant to end users, e.g. docs only)

[codecov]

Codecov Report

Attention: Patch coverage is 96.55172% with 2 lines in your changes missing coverage. Please review.

Project coverage is 39.27%. Comparing base (ccdcab9) to head (c80414d).
Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
api/python/quilt3/packages.py	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4216      +/-   ##
==========================================
+ Coverage   39.16%   39.27%   +0.10%     
==========================================
  Files         775      775              
  Lines       35086    35132      +46     
  Branches     5294     5294              
==========================================
+ Hits        13743    13798      +55     
+ Misses      20146    20137       -9     
  Partials     1197     1197              

Flag	Coverage Δ
api-python	91.29% <96.55%> (+0.18%)	⬆️
catalog	14.57% <ø> (ø)
lambda	92.02% <ø> (ø)

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Copilot reviewed 3 out of 3 changed files in this pull request and generated no suggestions.

[nl0]

looks good, some nitpicks

[sir-sigurd]

could you please start use common convention of referencing GH issues in PR titles/commit messages?

e.g. fix #NNN: some message

[nl0]

lgtm. @sir-sigurd pls approve if looks good to you too