Worker: no error handling on fetch:credential

[josephjclark]

Just like #590, the Worker doesn't have very good error handling around fetch:credential. If for some reason a credential can't be returned (like with this Oath bug we're seeing), only bad things will happen.

At the time of writing that's manifesting as the Run being marked as Lost.

I am a bit concerned that the worker will get the run:error event before the run:start event. I think this is legit - we can't even start the run if we can't load the credentials.

(later, credentials and dataclips will be loaded on demand, rather than preloaded, so that becomes kinda moot)

This is all closely related to the dataclip stuff - see #595

[josephjclark]

I actually think the 1-0 branch is handling this a lot better because it adds error handling to the underlying helper function.

[josephjclark]

Yes, in fact, I think in 1.0 the credential will throw or timeout, which will trigger a run:error. The error message might be cryptic (or might not!) but I think it'll hold up and the run will error without being Lost

[josephjclark]

I think the bigger question is: what error reason do we return if a credential failed to load?

If it's because the credential is hosted externally and is out of date or invalid, that feels like a crash to me.