refactor: ♻️ add input checks in simulate (#184)

# Description

Just to be consistent - we check inputs in the other functions.

## Checklist

- [X] Ran `just run-all`

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: signekb

R/simulate.R

@@ -17,11 +17,16 @@
 #' @examples
 #' simulate_register(register = "kontakter", year = c("1999", "2000"))
 simulate_register <- function(register, year = "", n = 1000) {
+  checkmate::assert_string(register)
+  checkmate::assert_character(year)
+  checkmate::assert_number(n)
+
   names <- dplyr::if_else(
     year == "",
     register,
     paste(register, year, sep = "_")
   )
+
   purrr::map(names, \(name) {
     osdc::simulate_registers(registers = register, n = n)[[1]]
   }) |>
@@ -42,12 +47,18 @@ simulate_register <- function(register, year = "", n = 1000) {
 #' @examples
 #' save_as_sas(data_list = simulate_register("kontakter", "2020"), path = fs::path_temp())
 save_as_sas <- function(data_list, path) {
+  checkmate::assert_list(data_list, names = "named")
+
   fs::dir_create(path, recurse = TRUE)
+
   purrr::iwalk(data_list, \(df, name) {
+    # Suppress warning bc `write_sas()` is deprecated, but good enough for our
+    # use case.
     suppressWarnings(haven::write_sas(
       df,
       fs::path(path, glue::glue("{name}.sas7bdat"))
     ))
   })
+
   invisible(path)
 }