pathologic geom tests

[YeungOnion]

added some pathological tests so we can have somewhere to point about when behavior gets funky due to unguarded calls.

• test: add some geometric pathological tests
• fix: format assertion message with precision

[codecov]

Codecov Report

❌ Patch coverage is 0% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.77%. Comparing base (9632b34) to head (2d9f2e2).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/distribution/geometric.rs	0.00%	23 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #402      +/-   ##
==========================================
- Coverage   94.93%   94.77%   -0.17%     
==========================================
  Files          61       61              
  Lines       13379    13402      +23     
==========================================
  Hits        12702    12702              
- Misses        677      700      +23     

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