Don't use R macro

[richfitz]

R_FINITE is not available without using R's headers, and should not be used in this context

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.57%. Comparing base (be63264) to head (1ad7e33).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #116   +/-   ##
=======================================
  Coverage   99.57%   99.57%           
=======================================
  Files          73       73           
  Lines        5582     5582           
=======================================
  Hits         5558     5558           
  Misses         24       24           

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