BUG: download error for days past end of database

[aburrell]

Description

The historic F10.7 data base will raise a JSON error if you ask for a time when they don't have data.

To Reproduce this bug:

Steps to reproduce the behavior:

import pysat
from pysatSpaceWeather.instruments import sw_f107

f107_hist = pysat.Instrument(inst_module=sw_f107, tag='historic')
f107_hist.download(start=f107_hist.lasp_stime, stop=f107_hist.today(), freq='MS')

Test configuration

• OS: OS Big Sur
• Version: Python 3.9
• Other details about your setup that could be relevant

Possible solutions

1) Consider this a feature, since it's clear nothing has been downloaded 2) And an end date attribute to the Instrument (similar to the lasp_stime attribute) 3) Something else?

[jklenzing]

just pushed a new branch with a possible solution: f107_patch

downstream of #85