Bare theophylline controller creation call fails

[tynsci]

Describe the bug command theophylline() throws an error:

> theophylline()
Error in plot_pmx.pmx_gpar(gp, p, bloq_cens) : 
  'list' object cannot be coerced to type 'double'

To Reproduce theophylline()

Expected behavior controlller to be created without error

Package and platform (please complete the following information):

• Operating system: linux (NixOS and Ubuntu tested)
• ggplot2 version: 3.4.2
• ggPMX version: development at commit ee65d769ee832779dd0fa5696138df407132734a