Applying Adv-R, 1: Shiny Error Modals

ShinyErrorModals.R

observeEvent(input$run_main, {
  
  showModal(modalDialog(title = "Please wait", "Loading Data!"))

    df_reactivevalues <- tryCatch(
      fn_loaddata(df_reactivevalues),
      error = function(e) {
        Sys.sleep(2)
        showModal(modalDialog(title = "Oh no, we've found an error!", e$message))},
      warning = function(e) {
        Sys.sleep(2)
        showModal(modalDialog(title = "Warning", e$message))}
    )
  
    removeModal()
  })

Useful for a) passing descriptive error messages to app users and b) for debugging unexpected problems.