Review automatic weekly data type conversion

[dshemetov]

epidatr automatically converts weeks to dates, using MMWRweeks, but unfortunately we don't have a convention as to what weeks mean in covidcast-indicators, so we should be careful about this.

Either:

• Double check which indicators actually use epiweeks and maybe allow conversions to date markers (e.g. first day of week)
• Don't convert and keep as integer, leave it up to the user

[dsweber2]

https://cmu-delphi.github.io/delphi-epidata/api/covidcast_times.html notionally if its week its an MMWR week

[dajmcdon]

Possibly related, or separate issue:

library(epidatr)
nhsn <- pub_covidcast(
  source = "nhsn",
  signals = "confirmed_admissions_flu_ew",
  geo_type = "state",
  time_type = "epiweek",
  time_values = "*",
  issues = "*"
)
#> Error in create_epidata_field_info("time_value", switch(time_type, day = "date", : is.character(type) && length(type) == 1 && type %in% c("text",  .... is not TRUE

It would be nice if this "worked" (say catching that "epiweek" should be "week") or at minimum, gave a more informative error message.

This particular case is especially confounding since the signal has the _ew suffix indicating "epiweek".