Fixing nvars in addCorGen

[kgoldfeld]

No description provided.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 2f7a2b1 is merged into main:

•   :ballot_box_with_check:define_data: 19.8ms -> 20ms [-0.46%, +2.45%]
•   :ballot_box_with_check:dist_beta: 259ms -> 258ms [-0.79%, +0.39%]
•   :ballot_box_with_check:dist_binary: 13.8ms -> 13.9ms [-0.68%, +1.7%]
•   :ballot_box_with_check:dist_binomial: 18.5ms -> 18.5ms [-1.18%, +1.13%]
• ❗🐌dist_categorical: 84.4ms -> 84.9ms [+0.07%, +1.13%]
•   :ballot_box_with_check:dist_exponential: 13.9ms -> 13.8ms [-1.58%, +0.68%]
•   :ballot_box_with_check:dist_gamma: 25.4ms -> 25.4ms [-0.48%, +0.73%]
•   :ballot_box_with_check:dist_mixture: 279ms -> 278ms [-0.53%, +0.27%]
•   :ballot_box_with_check:dist_normal: 16.6ms -> 16.8ms [-0.61%, +1.85%]
•   :ballot_box_with_check:gen_all_dists: 65.4ms -> 65.3ms [-1.43%, +1.29%]
  Further explanation regarding interpretation and methodology can be found in the documentation.