Leafet doesn't display viridis colors in legend

I have a problem plotting the colors of the legend using the viridis palette: the colors are not displayed although the legend labels are.

I tested the same code under Ubuntu with Shiny Server v1.4.2.786 with Node.js v0.10.40 (it doesn't display the viridis colors) and under MacOS (it does correctly).

The details of the Ubuntu R session:

R version 3.3.1 (2016-06-21)Platform: x86_64-pc-linux-gnu (64-bit)Running under: Ubuntu 15.10leaflet_1.0.1 shiny_0.13.2  viridis_0.3.4

This is the legend that doesn't display the colors

    leaflet() %>% addTiles() %>% addLegend(      position = 'bottomright',      colors = viridis(8),       labels = viridis(8), opacity = 1)

while this works also on the Ubuntu machine

    leaflet() %>% addTiles() %>% addLegend(      position = 'bottomright',      colors = rgb(t(col2rgb(palette())) / 255),       labels = palette(), opacity = 1)

It really seems to be a problem with the color codes of the viridis palette (I tried copying/pasting them in a character vector).

A working example

library(shiny)library(leaflet)library(viridis)r_colors <- rgb(t(col2rgb(colors()) / 255))names(r_colors) <- colors()ui <- fluidPage(  leafletOutput("mymap"))server <- function(input, output, session) {  output$mymap <- renderLeaflet({    leaflet() %>% addTiles() %>% addLegend(      position = 'bottomright',      colors = viridis(8),       labels = viridis(8), opacity = 1)  })}shinyApp(ui, server)