Incorrectly found a critical issue

[joaoabr]

The first example provided in the vignette does not seem to work with version 0.0.0.9005, as "time" and "amt" are assumed to be user-defined variables instead of dataset-related. See below:

m <- model() +
  prm_log_normal("v") +
  prm_log_normal("cl") +
  obs_additive(conc~amt/v*exp(-cl/v*time)) 

render(m)

Gives the output:

Error: Critical issues found
x The model contains 1 issue that need to be fixed before rendering it.
i Get a list of issue by running: `check(m)`
Run `rlang::last_error()` to see where the error occurred.

And

check(m)

GIves the output:

! 1 issue
  1. Undefined variables 'time' and 'amt' in observation