addDepot() fails if the centralLine is at the beginning or end of the model

[billdenney]

At the beginning gives an incorrect model output.

mymodel <- function() {
  description <- "One compartment PK model with linear clearance using differential equations"
  dosing<-c("central", "depot")
  ini({
    lcl <- 1 ; label("Clearance (CL)")
    lvc  <- 3.45 ; label("Central volume of distribution (V)")
    propSd <- 0.5 ; label("Proportional residual error (fraction)")
  })
  model({
    d/dt(central) <- exp(lcl)/exp(lvc)*central

    central ~ prop(propSd)
  })
}

mymodel |>
  addDepot(fdepot = 1)

[billdenney]

At the end gives an error:

mymodel <- function() {
  description <- "One compartment PK model with linear clearance using differential equations"
  dosing<-c("central", "depot")
  ini({
    lcl <- 1 ; label("Clearance (CL)")
    lvc  <- 3.45 ; label("Central volume of distribution (V)")
    propSd <- 0.5 ; label("Proportional residual error (fraction)")
  })
  model({
    central ~ prop(propSd)
    d/dt(central) <- exp(lcl)/exp(lvc)*central
  })
}

mymodel |>
  addDepot(fdepot = 1)