Validate in Shiny doesn't work as expected when making a highcharter treemap

Question

When trying to make a highcharter treemap in Shiny I encountered this strange thing. When the condition for validate a highchart isn't met I get this interactive text treemap togehter with my validate message (instead of just the text).

Am I doing something wrong or is this just a bug within Highchart?

## app.R ##
require(shiny)
require(treemap)
require(highcharter)
ui <- fluidPage(numericInput(inputId = "n",
                             "Input number", value = 1),
                highchartOutput("tree"))

server <- function(input, output, session) {
  data(GNI2014)
  tm <-  treemap(
    GNI2014,
    index = c("continent", "iso3"),
    vSize = "population",
    vColor = "GNI",
    type = "value"
  )
  output$tree <- renderHighchart({
    validate(need(input$n == 1, "Please input number 1"))
    hctreemap(tm = tm)
  })
}

shinyApp(ui, server)

Answer 1

Here is a work around using the renderUI

## app.R ##
require(shiny)
require(treemap)
require(highcharter)
ui <- fluidPage(numericInput(inputId = "n","Input number", value = 1),
                htmlOutput("tree"))

server <- function(input, output, session) {
  data(GNI2014)
  tm <-  treemap(
    GNI2014,
    index = c("continent", "iso3"),
    vSize = "population",
    vColor = "GNI",
    type = "value"
  )


  output$tree <- renderUI({
    validate(need(input$n == 1, "Please input number 1"))
    if(input$n != 1){
      h1 <- highchart()
    }
    else{
      h1 <- hctreemap(tm = tm)
    }
    hw_grid(h1,rowheight = 390)
  })

}

shinyApp(ui, server)