FeatureLayer with dynamic style doesn't work via leafletProxy()

[krlmlr]

Passing JS() in featureLayerOptions() doesn't work, but passing JSON (via list()) or interacting with the leaflet() (instead of the leafletProxy()) works.

The following minimalistic example app shows the problem. Switch between these modes by changing the value of demo in the first line. Shiny is required to replicate.

# Example works with "map" and "json", doesn't work with "js"
demo <- "js" # "map", "json", "js"

library(shiny)
library(leaflet)
library(leaflet.esri)

# Define UI for application that draws a histogram
ui <- fillPage(
    leafletOutput("map")
)

# Define server logic required to draw a histogram
server <- function(input, output, session) {

    output$map <-
        renderLeaflet({

            map <-
                leaflet() %>%
                addEsriBasemapLayer(esriBasemapLayers$Gray) %>%
                setView(-118.22, 33.836, 8)

            if (demo == "map") {
                map <-
                map %>%
                    addEsriFeatureLayer(
                        layerId = "Map object",
                        url = "https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/USA_Congressional_Districts/FeatureServer/0",
                        fillOpacity = 0.5,
                        options = featureLayerOptions(
                            simplifyFactor = 0.5, precision = 5,
                            style = JS('{ fillColor: "green" }')))
            }
            map

        })

    if (demo == "json") {
        onFlushed(function() server_json(input, output, session))
    } else if (demo == "js") {
        onFlushed(function() server_js(input, output, session))
    } else if (demo != "map") {
        stop()
    }
}

server_json <- function(input, output, session) {
    leafletProxy("map") %>%
        addEsriFeatureLayer(
            layerId = "Proxy JSON",
            url = "https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/USA_Congressional_Districts/FeatureServer/0",
            fillOpacity = 0.5,
            options = featureLayerOptions(
                simplifyFactor = 0.5, precision = 5,
                style = list(fillColor = "green")
            )
        )
}

server_js <- function(input, output, session) {
    leafletProxy("map") %>%
        addEsriFeatureLayer(
            layerId = "Proxy JS",
            url = "https://services.arcgis.com/P3ePLMYs2RVChkJx/arcgis/rest/services/USA_Congressional_Districts/FeatureServer/0",
            fillOpacity = 0.5,
            options = featureLayerOptions(
                simplifyFactor = 0.5, precision = 5,
                style = JS('{ fillColor: "green" }')
            )
        )
}

# Run the application
shinyApp(ui = ui, server = server)