unclear error message

[BFalquet]

It is not really an error but the message is missleading, the issue is that the number of levels in the variable should be >= 1 be It is actually ok if the variable is of length 0. (and there is no bug if it is a character.)

Should we be more tolerant, should we improve the error message or force the users to use factors ?

library(chevron)
#> Registered S3 method overwritten by 'tern':
#>   method   from 
#>   tidy.glm broom
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union
proc_data <- syn_data
proc_data$addv <- proc_data$addv[NULL, ]

preprocess(pdt01) <-
  function(adam_db, ...) {
    adam_db$addv <- adam_db$addv %>%

      mutate(across(all_of(c(
        "DVSCAT",
        "DVTERM"
      )), ~ reformat(.x, nocoding))) %>%
      mutate(
        DVSCAT = with_label(
          .data$DVSCAT,
          "Category"
        ),
        DVTERM = with_label(
          .data$DVTERM,
          "Category"
        )
      ) %>% 
      mutate(DVTERM = stringr::str_wrap(DVTERM, width = 50))
    adam_db %>% dunlin::log_filter(.data$DVCAT == "MAJOR", "addv")
  }

run(pdt01, proc_data)
#> Error in tryCatch(withCallingHandlers({: 1 assertions failed:
#>  * Variable 'adam_db$addv$DVTERM': Must have length >= 1, but has
#>  * length 0.
Created on 2024-07-01 with [reprex v2.1.0](https://reprex.tidyverse.org/)