Calls to get_*() functions that use identifiers should auto-clean NA values.

[SimonGoring]

Currently a call to (e.g.) get_datasets() that contains NA values results in a failing call due to the passing of a NULL value. Note, this may overlap with an issue in the Neotoma API.

reprex:

library(neotoma2)
datasetids <- c(1,2,3,4,NA,6)
output <- get_datasets(datasetids)

Returns:

Error in neotoma2::parseURL(base_url, ...) : 
  Internal Server Error (HTTP 500). Failed to Could not connect to the Neotoma API.
                    Check that the path is valid, and check the current
                     status of the Neotoma API services at
                      http://data.neotomadb.org.

Should return a valid sites object.