rmarkdown self_contained: false doesn't render image

[tim-salabim]

When opened in a browser the following .Rmd fails with

Fetch API cannot load file:///C:/Users/Tim/Desktop/test_georaster_files/stars-0.0.1/stars_layer.tif. URL scheme must be "http" or "https" for CORS request.

    ---
    title: "Some title"
    author: "Some author"
    date: "Some date"
    output: 
      html_document:
        self_contained: false
    ---
    
    ```{r setup, include=FALSE}
    knitr::opts_chunk$set(echo = TRUE)
    ```
    
    
    ```{r geotiff}
    library(stars)
    library(leaflet)
    library(leafem)
    
    tif = system.file("tif/L7_ETMs.tif", package = "stars")
    (x1 = read_stars(tif))
    strs = st_warp(x1, crs = 4326)
    fl = tempfile(fileext = ".tif")
    write_stars(strs, fl)
    pal = grDevices::colorRampPalette(hcl.colors(9, "viridis"))
    colops = colorOptions(
      palette = pal
      , domain = c(-1, 1)
      , na.color = "#bebebe"
      , breaks = NULL
    )
    
    ndvi = function(x) (x[4] - x[3]) / (x[4] + x[3])
    
    leaflet() %>%
      addTiles() %>%
      addGeotiff(
        file = fl
        , group = "stars"
        , resolution = 64
        , arith = ndvi
        , colorOptions = colops
      )
    ```

If self_contained: true it works as apparently all attachements are being included in the html document. This is fine for small images, but will fail miserably for even medium sized tif filesf I fear.

To get this to work we need the latest dev version of leafem:

remotes::install_github("r-spatial/leafem")

I assume that this isn't working because the .Rmd is not served via localhost. Not sure how to solve this...