Minor improvements to hictk dump

[robomics]

The endless loop was detected while developing #217.

[codecov]

Codecov Report

Attention: Patch coverage is 33.33333% with 36 lines in your changes missing coverage. Please review.

Project coverage is 75.65%. Comparing base (ff82e76) to head (10a28e0).
Report is 4 commits behind head on main.

Files	Patch %	Lines
src/hictk/dump/dump_common.cpp	30.00%	29 Missing and 6 partials ⚠️
src/hictk/dump/dump.cpp	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #229      +/-   ##
==========================================
- Coverage   75.85%   75.65%   -0.21%     
==========================================
  Files         140      140              
  Lines       11580    11615      +35     
  Branches     1311     1321      +10     
==========================================
+ Hits         8784     8787       +3     
- Misses       1717     1745      +28     
- Partials     1079     1083       +4     

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