fix: Handle many missing top-level packages

[jjerphan]

Description

Type of Change

• Bugfix
• Feature / enhancement
• CI / Documentation
• Maintenance

Checklist

• My code follows the general style and conventions of the codebase, ensuring consistency
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have run pre-commit run --all locally in the source folder and confirmed that there are no linter errors.
• I have added tests that prove my fix is effective or that my feature works
• New and existing tests pass locally with my changes

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.41%. Comparing base (df10fc2) to head (f15f7f1).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
libmamba/src/solver/problems_graph.cpp	90.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4361      +/-   ##
==========================================
+ Coverage   55.38%   55.41%   +0.03%     
==========================================
  Files         243      243              
  Lines       30374    30389      +15     
  Branches     3257     3261       +4     
==========================================
+ Hits        16822    16841      +19     
+ Misses      13549    13545       -4     
  Partials        3        3              

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