plotly not plotting geom_sf data, "Error in st_coordinates.sfc(sf::st_geometry(model)) : not implemented for objects of class sfc_GEOMETRY"

Hi,

I am trying to convert this geom_sf plot to plotly, but I keep receiving an error:

library(ggplot2)
library(sf)
library(geojsonsf)
library(plotly)

dk_map <- geojson_sf("https://raw.githubusercontent.com/moestrup/covid19/master/test.json")

mainland <- ggplot(data=dk_map) +
  geom_sf()

mainland

ggplotly(mainland)

sessionInfo()

Gives the following output:

> dk_map <- geojson_sf("https://raw.githubusercontent.com/moestrup/covid19/master/test.json")
> mainland <- ggplot(data=dk_map) +
+   geom_sf()
> mainland

> ggplotly(mainland)
Error in st_coordinates.sfc(sf::st_geometry(model)) : 
  not implemented for objects of class sfc_GEOMETRY
> sessionInfo()
R version 3.6.3 (2020-02-29)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 10 x64 (build 17763)

Matrix products: default

locale:
[1] LC_COLLATE=English_United Kingdom.1252  LC_CTYPE=English_United Kingdom.1252    LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C                            LC_TIME=English_United Kingdom.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] plotly_4.9.2.9000 geojsonsf_1.3.3   sf_0.9-3          ggplot2_3.3.0    

loaded via a namespace (and not attached):
 [1] Rcpp_1.0.4         pillar_1.4.3       compiler_3.6.3     class_7.3-15       tools_3.6.3        digest_0.6.25      viridisLite_0.3.0 
 [8] jsonlite_1.6.1     lifecycle_0.2.0    tibble_3.0.0       gtable_0.3.0       pkgconfig_2.0.3    rlang_0.4.6        DBI_1.1.0         
[15] cli_2.0.2          rstudioapi_0.11    curl_4.3           e1071_1.7-3        httr_1.4.1         withr_2.1.2        dplyr_0.8.5       
[22] htmlwidgets_1.5.1  vctrs_0.3.0        classInt_0.4-3     grid_3.6.3         tidyselect_1.0.0   glue_1.3.2         data.table_1.12.8 
[29] R6_2.4.1           fansi_0.4.1        farver_2.0.3       tidyr_1.0.2        purrr_0.3.3        magrittr_1.5       scales_1.1.0      
[36] ellipsis_0.3.0     htmltools_0.4.0    units_0.6-6        assertthat_0.2.1   colorspace_1.4-1   KernSmooth_2.23-16 lazyeval_0.2.2    
[43] munsell_0.5.0      crayon_1.3.4       Cairo_1.5-12      
> 

I thought this was related to issue #1659, and tried installing the newest version of plotly from github (4.9.2.9000) but am still seeing the error above.

Start with the supplied ggplotly(mainland) reproducer and the st_coordinates.sfc error for sf::st_geometry(model). Trace how geom_sf data reaches the ggplotly entry point, then determine how sfc_GEOMETRY objects are handled. Done means the reproducer converts without the reported error and produces the expected interactive map.