Trailing comma in `theme()` causing error in 3.5.0

[kylebutts]

I'm on the most recent commit and trailing comma support in theme() is not working. I'm not sure why since it seems to call list2() which allows for trailing comments? I have traced it back to this PR: #5543

Commit a4be39d produces:

library(ggplot2)
theme(
  title = element_text(size = 12), 
)
#> Error in `list2()`:
#> ! Argument 1 can't be empty.

Commit right before 6df5cd4:

library(ggplot2)
theme(
  title = element_text(size = 12), 
)
#> List of 1
#>  $ title:List of 11
#>   ..$ family       : NULL
#>   ..$ face         : NULL
#>   ..$ colour       : NULL
#>   ..$ size         : num 12
#>   ..$ hjust        : NULL
#>   ..$ vjust        : NULL
#>   ..$ angle        : NULL
#>   ..$ lineheight   : NULL
#>   ..$ margin       : NULL
#>   ..$ debug        : NULL
#>   ..$ inherit.blank: logi FALSE
#>   ..- attr(*, "class")= chr [1:2] "element_text" "element"
#>  - attr(*, "class")= chr [1:2] "theme" "gg"
#>  - attr(*, "complete")= logi FALSE
#>  - attr(*, "validate")= logi TRUE

[teunbrand]

Hi there, thanks for the report! We are aware this was an issue and it has been fixed in #5604.