countrycode(NA, "genc2c", "country.name")
Error in countrycode(NA, "genc2c", "country.name") :
sourcevar must be a character or numeric vector. This error often
arises when users pass a tibble (e.g., from dplyr) instead of a
column vector from a data.frame (i.e., my_tbl[, 2] vs. my_df[, 2]
vs. my_tbl[[2]])