safeError behavior in observeEvent vs. eventReactive

safeerror.R

library(shiny)
library(bslib)
library(ggplot2)

ui <- page_sidebar(
  title = h1(
    class = "bslib-page-title",
    "Errors when bins == 29"
  ),

  sidebar = sidebar(
    title = "Histogram controls",
    numericInput("bins", "Number of bins", 30),
    actionButton("submit_button", "Submit"),
    actionButton("send_button", "Send")
  ),

  card(
    card_header("Histogram"),
    plotOutput("p")
  )
)

server <- function(input, output) {
  make_plot <- function() {
    ggplot(iris) +
      geom_histogram(aes(Sepal.Length), bins = input$bins) +
      theme_bw(base_size = 20)
  }
  observeEvent(input$submit_button, {
    output$p <- renderPlot({ 
      if (input$bins == 29) stop(safeError("Error in stuff"))
      make_plot() 
    })
  })
  xx <- eventReactive(input$send_button, {
    if (input$bins == 29) stop(safeError("Error in things"))
    make_plot()
  })
  output$p <- renderPlot({ xx() })
}

shinyApp(ui, server)