r - 单击操作按钮时使用 renderUI 函数显示仪表板页面

Question

在我的代码中，当单击加载场景按钮时，它应该显示一个仪表板。但我收到错误“'closure' 类型的对象不是子集”。我知道堆栈溢出中已经提出了很多问题，但我无法得到这些中的任何一个这是我的代码

library("shiny")
  library("shinydashboard")
ui <- fluidPage(


 actionButton("create_scenario", "Create Scenario"),
  actionButton("load_scenario","load scenario"),
 uiOutput("input"),
 uiOutput("inputs")
   )

  server <- function(input, output,session) {

 observeEvent(input$create_scenario,{

   output$input <- renderUI({
     textInput("txtInput","Enter Scenario Name","Enter name as scenario         
(number of senario created +1)")
    })


 })

  observeEvent(input$load_scenario,{

  output$inputs <- renderUI({
  # textInput("txtInput","Enter Scenario Name","Enter name as scenario  
 #(number of senario created +1)")
        dashboardPage(
       dashboardHeader(title = "Basic dashboard"),
      dashboardSidebar(),
       dashboardBody(
     # Boxes need to be put in a row (or column)
     fluidRow(
       box(plotOutput("plot1", height = 250)),

       box(
         title = "Controls",
         sliderInput("slider", "Number of observations:", 1, 100, 50)
      ))))

  histdata <- rnorm(500)
output$plot1 <- renderPlot({
  data <- histdata[seq_len(input$slider)]
hist(data)
})

 } )


 })
}
shinyApp(ui, server)