Standardize process exit codes

[brandenrodgers]

Description and Context

Following up this PR here: #565

We would like to have three different exit codes:

• 0: A successful run
• 1: There was a config problem or an internal error
• 2: There are warnings or validation issues

I'm adding some utils for us to use around the repo to make sure that we're using the exit codes consistently. There are a lot of places that will need to be updated, so I haven't done that yet. I'm showing three different patterns that we could use. I don't feel super strongly about any of them, but I figured I'd check in with everyone before picking one of them.

Here's some more context. This is how the ESLint CLI handles their error codes.

Screenshots

TODO

• Pick a pattern, and update all the commands to use it

Who to Notify

cc/ @gcorne

[gcorne]

My preference is the enum with process.exit() because I think it makes it clearer that execution will stop at that point.

[anthmatic]

My preference is the enum with process.exit() because I think it makes it clearer that execution will stop at that point.

I second this

[anthmatic]

Looks good