`compare_to_cran()` returns error when `rcmdcheck` object is passed and the `flavours` argument is not specified

[mnkwarshie]

Hello!

I hope you're doing well. In using the compare_to_cran() function, I have found that when the flavours argument is not specified, the function returns an error instead of returning all platforms as the reference manual states. This can be observed in my example below. However, when a specific platform is passed to the flavours argument, the function seems to work as intended.

Is this behavior expected?

library(rcmdcheck)

sessionInfo()
#> R version 4.5.2 (2025-10-31)
#> Platform: x86_64-pc-linux-gnu
#> Running under: Rocky Linux 8.10 (Green Obsidian)
#> 
#> Matrix products: default
#> BLAS:   /opt/R/openval/2026.03.00/4.5.2/lib64/R/lib/libRblas.so 
#> LAPACK: /opt/R/openval/2026.03.00/4.5.2/lib64/R/lib/libRlapack.so;  LAPACK version 3.12.1
#> 
#> locale:
#>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
#>  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
#>  [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
#>  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
#>  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
#> [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       
#> 
#> time zone: Etc/UTC
#> tzcode source: system (glibc)
#> 
#> attached base packages:
#> [1] stats     graphics  grDevices utils     datasets  methods   base     
#> 
#> other attached packages:
#> [1] rcmdcheck_1.4.0
#> 
#> loaded via a namespace (and not attached):
#>  [1] desc_1.4.3        digest_0.6.39     R6_2.6.1          fastmap_1.2.0    
#>  [5] xfun_0.54         glue_1.8.0        knitr_1.50        htmltools_0.5.8.1
#>  [9] rmarkdown_2.30    lifecycle_1.0.4   ps_1.9.1          cli_3.6.5        
#> [13] xopen_1.0.1       processx_3.8.6    callr_3.7.6       reprex_2.1.1     
#> [17] withr_3.0.2       compiler_4.5.2    rprojroot_2.1.1   prettyunits_1.2.0
#> [21] rstudioapi_0.17.1 tools_4.5.2       pkgbuild_1.4.8    curl_7.0.0       
#> [25] evaluate_1.0.5    yaml_2.3.11       rlang_1.1.6       fs_1.6.6

# download and untar the rcmdcheck tarball
download.packages("rcmdcheck", destdir = tempdir(), type = "source")
#>      [,1]        [,2]                                    
#> [1,] "rcmdcheck" "/tmp/RtmpCIM7Cx/rcmdcheck_1.4.0.tar.gz"
tarball <- list.files(tempdir(), pattern = "rcmdcheck.*\\.tar\\.gz", full.names = TRUE)

# create rcmdcheck object
chk <- rcmdcheck(tarball, quiet = TRUE)

# default usage as described in the reference manual (pg. 4)
compare_to_cran(chk)
#> Error in length(handles) == urls || length(handles) == 0: 'length = 14' in coercion to 'logical(1)'

# specifying a particular platform
compare_to_cran(chk, flavours = "r-release-linux-x86_64")
#> ── R CMD check comparison ───────────────────────────────── rcmdcheck 1.4.0 ────
#> Status: OK