Always show data for sensors and handle sensor errors

[fungjj92]

Overview

The app will show the most up to date data, and we want that to be the case when sensor requests fail too. #20 set up initial data retrieval and this PR deepens that work by adding error handling.

The fall through process prefers in this order:

most recent real data of:

• live sensor data as recent as exists
• quarterly water quality data

else:

• stale saved data
• dummy default values

The dummy values I based off of current-ish values I was seeing from each sensor but that don't have any meaning really.

Connects #59

Demo

Notes

I don't feel great about it, but in order to get data from the USGS APIs when they fail, we need to supply a starting date querystring, which is the last known date that the sensor has data. I added those dates to constants. They will always work, but become outdated over time insofar that we'll poll for more data than we need. I did not find a programatic and dynamic way to discover these dates.

I plan to rebase on #62 before merge

Testing Instructions

./scripts/server and see that the redux store has real data for all 3 sensors !

Please logically step through the pollSensor action and double check what I've done.

[fungjj92]

Rebased on develop including #62, and tested. Appears fine 🤞

[caseycesari]

This appears to be working as we need it. Good job! I also have concerns about the fixed "last known data date", but I'm not sure how to get around that at the moment. Perhaps it's worth creating an issue with the notes, so that we can discuss alternative approaches in the future.

Most of my comments are about clean-up related stuff. Particularly, it looks like Prettier hasn't been run through the changes (details here about setting up your editor: https://prettier.io/docs/en/editors.html).

[caseycesari]

Revisions look good! Tested it with and without wi-fi, and things look right.

[fungjj92]

Thanks for the reviews! Beat me to commenting.

Prettier is now set up the work on save on my editor, VS Code. I had installed several Prettier plugins last week, but ultimately I needed to npm install Prettier locally for the plugin(s) to work in the editor.

I created #63 to capture the discussion of date constants.