Increase coverage for bitcoin_client.rs

[CAGS295]

Summary of Changes

Line coverage 18.56% (72/388) -> 39.65% (205/517)

Testing

Risks

How were these changes tested?

What future testing should occur?

Checklist:

• [X] My code follows the style guidelines of this project
• [X] I have performed a self-review of my code
• [X] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [X] My changes generate no new warnings
• [X] I have added tests that prove my fix is effective or that my feature works
• [X] New and existing unit tests pass locally with my changes
• [X] Any dependent changes have been merged and published in downstream modules

[codecov[bot]]

Codecov Report

Attention: 24 lines in your changes are missing coverage. Please review.

Comparison is base (6470223) 43.44% compared to head (221fe2c) 44.82%. Report is 4 commits behind head on main.

Files	Patch %	Lines
romeo/src/system.rs	0.00%	20 Missing :warning:
romeo/src/bitcoin_client.rs	96.82%	4 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #330      +/-   ##
==========================================
+ Coverage   43.44%   44.82%   +1.37%     
==========================================
  Files          45       45              
  Lines        5467     5562      +95     
  Branches       47       47              
==========================================
+ Hits         2375     2493     +118     
+ Misses       3091     3068      -23     
  Partials        1        1              

Flag	Coverage Δ
unittests	76.61% <ø> (ø)

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[CLAassistant]

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