addCwres(fit, updateObject = TRUE, envir = parent.frame(1))

one.cmt <- function() {
  ini({
    ## You may label each parameter with a comment
    tka <- 0.45 # Log Ka
    tcl <- log(c(0, 2.7, 100)) # Log Cl
    ## This works with interactive models
    ## You may also label the preceding line with label("label text")
    tv <- 3.45; label("log V")
    ## the label("Label name") works with all models
    eta.ka ~ 0.6
    eta.cl ~ 0.3
    eta.v ~ 0.1
    add.sd <- 0.7
  })
  model({
    ka <- exp(tka + eta.ka)
    cl <- exp(tcl + eta.cl)
    v <- exp(tv + eta.v)
    linCmt() ~ add(add.sd)
  })
}

f <- try(nlmixr(one.cmt, theo_sd, "saem"))

print(f)

# even though you may have forgotten to add the cwres, you can add it to the data.frame:

if (!inherits(f, "try-error")) {
  f <- try(addCwres(f))
  print(f)
}

# Note this also adds the FOCEi objective function