从sliderInput控件R Shiny获取日期的索引时返回Inf错误

library(shiny)

ui <- fluidPage(
  sliderInput("dateSlider", "Select Date Range:",
              min = as.Date("2020-01-01"),
              max = as.Date("2020-12-31"),
              value = c(as.Date("2020-01-01"), as.Date("2020-12-31")),
              step = 1),
  verbatimTextOutput("selectedDates")
)

server <- function(input, output) {
  dateVector <- reactive({
    seq(as.Date("2020-01-01"), as.Date("2020-12-31"), by="days")
  })
  
  output$selectedDates <- renderPrint({
    dateRange <- input$dateSlider
    startIndex <- which(dateVector() == dateRange[1])
    endIndex <- which(dateVector() == dateRange[2])
    
    if (is.infinite(startIndex) || is.infinite(endIndex)) {
      showModal(modalDialog(
        title = "Error",
        "Invalid date range selected."
      ))
    } else {
      paste("Selected start index:", startIndex, "End index:", endIndex)
    }
  })
}

shinyApp(ui, server)