currently as_tibble() call needed to add additional_metadata

[ChloeYou]

ex3 <- jhu_csse_county_level_subset %>%
  filter(time_value > "2021-12-01", state_name == "Massachusetts") %>%
  slice_tail(n = 6)  %>% 
  as_tibble() %>% # needed to add the additional metadata
  mutate(state = rep(tolower("MA"),6)) %>%
  as_epi_df(additional_metadata = c(other_keys = "state"))

It's a bug that if we exclude the as_tibble() line, we silently ignore the additional_metadata arg.

Discovered in #103.

[rachlobay]

For the above ex, I think this could be because we are inputting an epi_df into as_epi_df (so lines 255 to 260 of epi_df.R, see below)...

#' @method as_epi_df epi_df
#' @describeIn as_epi_df Simply returns the `epi_df` object unchanged.
#' @export
as_epi_df.epi_df = function(x, ...) {
  return(x)
}

So it is not immediate to me as to what to do about the above bug as I was not the one to wrote that function(because perhaps it is important for other purposes)? But if it is not, that may be where to change to fix this issue.