Rejection Sampling - PMF Mean and Shift Bug

[danmcgraw94]

Describe the bug
Incorrectly handles pmf_mean and pmf_shift.

To Reproduce

pmf_sigma <- 0.5
pmf_shift <- 239
pmf_mean  <- 241.9
pmf_mu    <- log(pmf_mean - pmf_shift) - (pmf_sigma^2 / 2)
pmf_stage_lognormal(pmf_shift, pmf_mean)
#> Error in `pmf_stage_lognormal()`:
#> ! could not find function "pmf_stage_lognormal"
pmf_stage_lognormal(pmf_mean, pmf_shift)
#> Error in `pmf_stage_lognormal()`:
#> ! could not find function "pmf_stage_lognormal"

^{Created on 2026-05-18 with reprex v2.1.1}

Expected behavior
Error handling that prevents the log of a negative number

Actual behavior
Instead the functions only allow for pmf_shift > pmf_mean, only producing NaNs