core: fix typo in initFixedPoints, with unit test

[eckter]

While trying to reproduce the bug seen in #10488, I ended up with a unit test that failed, which led me to this typo (introduced in the previous PR)

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.80%. Comparing base (f0a5c8e) to head (506c15e).
Report is 11 commits behind head on dev.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev   #10498      +/-   ##
==========================================
- Coverage   81.80%   81.80%   -0.01%     
==========================================
  Files        1073     1073              
  Lines      106601   106606       +5     
  Branches      731      731              
==========================================
  Hits        87209    87209              
- Misses      19353    19358       +5     
  Partials       39       39              

Flag	Coverage Δ
editoast	74.28% <ø> (-0.02%)	⬇️
front	89.34% <ø> (+<0.01%)	⬆️
gateway	2.18% <ø> (ø)
osrdyne	3.28% <ø> (ø)
railjson_generator	87.50% <ø> (ø)
tests	87.05% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.