fetch_tbl() warning from vroom sometimes (when NA's are present?)

[dsweber2]

covid_hosp_state_timeseries(states = "MA", dates = "20200510") %>% fetch_tbl()

## Warning: One or more parsing issues, call `problems()` on your data frame for details,
## e.g.:
##   dat <- vroom(...)
##   problems(dat)

There are a number of calls where this happens, it appears to be NA's, not exactly sure. Will document more examples soon

cm <- covidcast_meta() %>%
  fetch_tbl()

fluview_meta() %>% fetch_tbl()