Fixed NAs in psis_r_eff

[VisruthSK]

Fixed NA issues in psis_r_eff by replacing NA values with 1s.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.90566% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.76%. Comparing base (119be4a) to head (bf7aec8).

Files with missing lines	Patch %	Lines
R/psis.R	84.90%	8 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #301      +/-   ##
==========================================
- Coverage   92.78%   92.76%   -0.02%     
==========================================
  Files          31       31              
  Lines        2964     2986      +22     
==========================================
+ Hits         2750     2770      +20     
- Misses        214      216       +2     

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[jgabry]

Looks good, thanks! I just made one comment about the message.

[n-kall]

I think the comment above the function can be updated to add this case

[jgabry]

This looks good. Will go ahead and merge. Thanks @VisruthSK.