should functions error early w/ empty args?
for example:
dataRetrieval::whatNWISsites()
Request failed [400]. Retrying in 1 seconds...
Request failed [400]. Retrying in 1 seconds...
For: https://waterservices.usgs.gov/nwis/site/?format=mapper
Error in getWebServiceData(urlCall, encoding = "gzip") :
Bad Request (HTTP 400).
Maybe it shouldn't try this call in the first place?