tagAssert 创建一个闪亮的应用程序时出错

Question

library(shiny)
library(shinydashboard)
library(maftools)
ui <- dashboardPage(
dashboardHeader( title = "Data Annotation"),
 dashboardSidebar(
   dashboardBody(
     fluidRow(
       tabItem(tabName = "File Input",
             fileInput("file1", "Choose File", multiple = FALSE, accept = c(".maf",".maf.gz"))),
       tabItem(tabName = "oncoplots",
            (plotOutput("oncoplots"))),
   )
   )
  )
)
server <- function(input, output) {
 usrvar <- reactive({
  validate(need(input$file1$datapath != "", "Please upload an MAF file."))
 if (is.null(input$file2$datapath)){
   read.maf(input$file1$datapath)}
 else {
   read.maf(maf = input$file1$datapath , clinicalData = input$file2$datapath)
}})
 aff <- reactive({
 lamlgh.maf = system.file('extdata', 'tcga_laml.maf.gz', package = 'maftools') 
 laml = read.maf(maf = laml.maf)
 faf <- list(getFields(laml))
 return(faf)
})
output$oncoplots <- renderPlot({
  oncoplot(maf = usrvar() , top = input$oncoslider)
})
}
shinyApp(ui = ui, server = server)

我正在尝试创建一个闪亮的应用程序来可视化图中的数据，但我收到此错误“ tagAssert(body, type = "div", class = "content-wrapper") 中的错误： 缺少参数“body”，没有默认值。不知道我是否遗漏了代码中的某些内容