Use a specific error class for Uplink connection errors

[nogates]

Hello there!

I'd like to ask if it would be possible to have a specific error class to signal errors when pulling supergraph schema from uplink.

Right now, when this happens, a generic error is thrown, and if we want to catch those errors, we need to match the error message, which seems a bit brittle (I wouldn't be surprised if that message is changed in the future).

Would it be possible to extend the Error class with a more specific name (something like UplinkFetchError), and export it, so we can check the name of that error instead of the message?

A bit of context, we plan on catching these errors on our Gateways. If Apollo Uplink is down, we can at least rescue from those errors and use a local schema instead, so our Gateways can still start up, even if the schema is an old one.

Thank you!

[nogates]

BTW, I didn't mention it, but I'd be happy to work on this and submit a PR if that's ok with you folks :)

[cpeacock]

Absolutely, we'd love to have you take a crack at it if you'd like! We did place this on a team's backlog but would love your contribution if you're able to give the time.

[trevor-scheer]

Resolved in #1473