Fix zero cost EOS bug

[ppinchuk]

Refactor left a bug that would crash program if any LCOE component is set to 0 (like VOC usually is). New default cost is None (NaN), which allows 0 values to pass through normally

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.59%. Comparing base (75ccf41) to head (5e128cb).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #458      +/-   ##
==========================================
+ Coverage   87.52%   87.59%   +0.06%     
==========================================
  Files         122      122              
  Lines       18070    18091      +21     
==========================================
+ Hits        15816    15846      +30     
+ Misses       2254     2245       -9     

Flag	Coverage Δ
unittests	87.59% <100.00%> (+0.06%)	⬆️

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