From 4d226713f2f0edb57326b3c93ac4e64c730c2062 Mon Sep 17 00:00:00 2001
From: Teun van den Brand <tahvdbrand@gmail.com>
Date: Thu, 22 May 2025 11:13:32 +0200
Subject: [PATCH] fallback for fallback

---
 R/scale-colour.R | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/R/scale-colour.R b/R/scale-colour.R
index 2580e57211..5f9faab7df 100644
--- a/R/scale-colour.R
+++ b/R/scale-colour.R
@@ -298,18 +298,14 @@ scale_backward_compatibility <- function(..., scale, aesthetic, type) {
     scale <- scale %||% fallback
   }
 
-  if (is_bare_string(scale)) {
-    if (scale == "continuous") {
-      scale <- "gradient"
-    }
-    if (scale == "discrete") {
-      scale <- "hue"
-    }
-    if (scale == "viridis") {
-      scale <- switch(
-        type, discrete = "viridis_d", binned = "viridis_b", "viridis_c"
-      )
-    }
+  if (is_bare_string(scale) || is.null(scale)) {
+    scale <- switch(
+      scale %||% type,
+      discrete = "hue",
+      viridis = switch(type, discrete = "viridis_d", binned = "viridis_b", "viridis_c"),
+      continuous = "gradient",
+      scale
+    )
 
     candidates <- paste("scale", aesthetic, scale, sep = "_")
     for (candi in candidates) {