linetype of `geom_edge_arc` can't be `factor` anymore with ggplot2 v4 (3.5.2.9002 main branch)

[pwwang]

packageVersion("ggplot2")
packageVersion("ggraph")

graph
df_nodes

library(ggraph)

p <- ggraph(graph, layout = "manual", x = df_nodes$x, y = df_nodes$y) +
    geom_edge_arc(aes(color = I(node.gender), linewidth = friendship, linetype = factor(type)))

p

With ggplot2 v3.5.2 (CRAN):

[1] ‘3.5.2’
[1] ‘2.2.2’

With ggplot2 v3.5.2.9002 (main branch):

[1] ‘3.5.2.9002’
[1] ‘2.2.2’

ERROR while rich displaying an object: Error in `as_discrete_pal()`:
Cannot convert `x` to a discrete palette.

Traceback:
1. sapply(x, f, simplify = simplify)
2. lapply(X = X, FUN = FUN, ...)
3. FUN(X[[i]], ...)
4. tryCatch(withCallingHandlers({
 .     if (!mime %in% names(repr::mime2repr)) 
 .         stop("No repr_* for mimetype ", mime, " in repr::mime2repr")
 .     rpr <- repr::mime2repr[[mime]](obj)
 .     if (is.null(rpr)) 
 .         return(NULL)
 .     prepare_content(is.raw(rpr), rpr)
 . }, error = error_handler), error = outer_handler)
5. tryCatchList(expr, classes, parentenv, handlers)
6. tryCatchOne(expr, names, parentenv, handlers[[1L]])
7. doTryCatch(return(expr), name, parentenv, handler)
8. withCallingHandlers({
 .     if (!mime %in% names(repr::mime2repr)) 
 .         stop("No repr_* for mimetype ", mime, " in repr::mime2repr")
 .     rpr <- repr::mime2repr[[mime]](obj)
 .     if (is.null(rpr)) 
 .         return(NULL)
 .     prepare_content(is.raw(rpr), rpr)
 . }, error = error_handler)
9. repr::mime2repr[[mime]](obj)
10. repr_text.default(obj)
11. paste(capture.output(print(obj)), collapse = "\n")
12. capture.output(print(obj))
13. withVisible(...elt(i))
14. print(obj)
15. `print.ggplot2::ggplot`(obj)
16. ggplot_build(x)
17. ggplot_build.ggraph(x)
18. NextMethod()
19. `ggplot_build.ggplot2::ggplot`(x)
20. npscales$set_palettes(plot@theme)
21. set_palettes(..., self = self)
22. as_discrete_pal(elem)
23. as_discrete_pal.default(elem)
24. cli::cli_abort("Cannot convert {.arg x} to a discrete palette.")
25. rlang::abort(message, ..., call = call, use_cli_format = TRUE, 
  .     .frame = .frame)
26. signal_abort(cnd, .file)

Attaching the graph and df_nodes data for debugging.

data.zip

Related: pwwang/plotthis#21

[teunbrand]

Smaller, self-contained reprex:

library(ggraph)
library(tidygraph)

gr <- create_notable('bull') |>
  activate(edges) |>
  mutate(g = sample(letters[1:3], n(), replace = TRUE))

ggraph(gr, 'stress') +
  geom_edge_link(aes(linetype = g))
#> Error in `as_discrete_pal()`:
#> ! Cannot convert `x` to a discrete palette.

^{Created on 2025-10-10 with reprex v2.1.1}

Should be fixed by tidyverse/ggplot2#6674.