Error in eval(lhs, parent, parent) : object 'countries_sf' not found >

Question

When I tried to run the code, for some reason, one of the objects "not found".

I tried to chance the name, run again, but it's always the same error.

The code:

countries_sf <- countries110 %>%
  st_as_sf()

pop_palette <- colorNumeric("viridis",
                            domain = countries_sf$gdp_md_est)

countries_sf %>%
  filter(! name == "Antarctica") %>%
  leaflet() %>%

the error message:

Error in eval(lhs, parent, parent) : object 'countries_sf' not found