I am trying to manipulate pasted data inside a shiny app. Here I tried to add a column as I would normally in R. But I get error message: Warning: Error in UseMethod: no applicable method for 'mutate' applied to an object of class "c('reactive.event', 'reactiveExpr', 'reactive', 'function')"

It makes it sound like I’m trying to manipulate a reactive.event object, so how do I manipulate the data.frame? I thought the output of read_clip_tbl() was a dataframe?

library(dplyr)
ui <- dashboardPage(
  dashboardHeader(),
  dashboardSidebar(
     actionButton("clip1", "Read from clipboard") 
  ),
  dashboardBody(
    tags$style(type="text/css",
               ".shiny-output-error { visibility: hidden; }",
               ".shiny-output-error:before { visibility: hidden; }"
    ),
    tableOutput("table1")
  )
)
server <- function(input, output, session) {
  table1 <- eventReactive(input$clip1, {
    read_clip_tbl()
    table1 %>% mutate(fourth = table1$first + table1$second)
  })
    output$table1<- renderTable({
      req(table1())
      table1()
    }) 
}

shinyApp(ui, server)