use logical `NA` that can be cast to character

R/ggplot2.R

   color = NULL,
   begin = 0,
   end = 1,
-  inverse = FALSE
+  inverse = FALSE,
+  na.value = NA
 ) {
   requires_package("ggplot2", "scale_xaringan_continuous")
   requires_package("scales", "scale_xaringan_continuous")
     palette = scales::gradient_n_pal(colors, values = NULL),
     rescaler = rescaler,
     oob = scales::censor,
+    na.value = na.value,
     ...
   )
 }

man/scale_xaringan.Rd

   color = NULL,
   begin = 0,
   end = 1,
-  inverse = FALSE
+  inverse = FALSE,
+  na.value = NA
 )
 
 scale_xaringan_fill_continuous(
 \item{begin}{Number in the range of \code{[0, 1]} indicating to which point in the color scale the smallest data value should be mapped.}
 
 \item{end}{Number in the range of \code{[0, 1]} indicating to which point in the color scale the largest data value should be mapped.}
+
+\item{na.value}{Color to be used for missing data points.}
 }
 \description{
 \ifelse{html}{\href{https://lifecycle.r-lib.org/articles/stages.html#maturing}{\figure{lifecycle-maturing.svg}{options: alt='[Maturing]'}}}{\strong{[Maturing]}}