An example illustrating a possible bug in the Leaflet package

leafletBug.R

library(shiny)
library(shinydashboard)
library(leaflet)

header <- dashboardHeader(
        title = "Example",
        titleWidth = "600px"
)

sidebar <- dashboardSidebar(width = "600px")


body <- dashboardBody(
        bootstrapPage(
                leafletOutput("map",height = "800px")
        )
)

ui <- dashboardPage(header, sidebar, body)        

server <- function(input, output) {
      
        
        output$map <- renderLeaflet({
                
                pal <- colorNumeric("Set2", quakes$mag)
                
                leaflet(quakes) %>% 
                        addTiles() %>%
                        fitBounds(~min(long), ~min(lat), ~max(long), ~max(lat)) %>% 
                        addCircles(radius = ~10^mag/10, weight = 1, color = "#777777",
                                   fillColor = ~pal(mag), fillOpacity = 0.7, popup = ~paste(mag)
                        )
        })
        
}

shinyApp(ui,server)