requesting rdb data from nonexistent site returns uncaught error

[mroberge]

• HydroFunctions version: 0.1.8dev

Description

Requesting data from a non-existent site will return a status code of 200, so everything is fine, you would think. But instead of returning an RDB table, you get a webpage with an error.

This link is for a non-existent site, 01581000:
https://waterdata.usgs.gov/pa/nwis/measurements?site_no=01581000&agency_cd=USGS&format=rdb_expanded

What I Did

hf.field_meas('01581000')

Possible Solution

Create a system for requesting data from the USGS that also handles errors.
Check for non-200 errors
Check the text in 200 codes for a <title>USGS NwisWeb error message</title>