simplify fallback_palette() args

Author: teunbrand

R/scale-.R

@@ -526,9 +526,7 @@ Scale <- ggproto("Scale", NULL,
     if (empty(df)) {
       return()
     }
-    if (is.null(self$palette)) {
-      self$palette <- fallback_palette(self$aesthetics[1], self$is_discrete())
-    }
+    self$palette <- self$palette %||% fallback_palette(self)
 
     aesthetics <- intersect(self$aesthetics, names(df))
     names(aesthetics) <- aesthetics

R/scales-.R

@@ -199,7 +199,7 @@ ScalesList <- ggproto("ScalesList", NULL,
         }
       }
 
-      elem <- elem %||% fallback_palette(scale$aesthetics[1], scale$is_discrete())
+      elem <- elem %||% fallback_palette(scale)
 
       if (!is.function(elem)) {
         cli::cli_warn(

R/utilities.R

@@ -777,7 +777,9 @@ as_unordered_factor <- function(x) {
   x
 }
 
-fallback_palette <- function(aes, discrete) {
+fallback_palette <- function(scale) {
+  aes <- scale$aesthetics[1]
+  discrete <- scale$is_discrete()
   if (discrete) {
     pal <- switch(
       aes,