Don't show empty slices as flag default values in help

[FollowTheProcess]

Summary

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.65%. Comparing base (6ad10c6) to head (33240c9).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #175      +/-   ##
==========================================
+ Coverage   90.48%   90.65%   +0.16%     
==========================================
  Files           5        5              
  Lines        1598     1627      +29     
==========================================
+ Hits         1446     1475      +29     
  Misses        106      106              
  Partials       46       46              

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