makeRequest() should throw instead of returning optional

[jbradforddillon]

Service.makeRequest() currently returns ServiceRequest?, which allows it to fail gracefully if anything is misconfigured. For example, if the Container doesn't include an endpoint provider, or if the endpoint requested doesn't exist.

In any failure case, the call site should be required to catch a more descriptive error and make the right decision. In most cases this will be a no op (same as it is today).

The big win here would be in unit testing and getting this plumbing working the first time.

[ktatroe]

I agree. Early Swift design patterns shied away from throws, but it's definitely become more accepted. I'd want to do a pass through the whole API to do an errors sweep. (Just got off doing that on another project, and have a lot better understanding of what makes a good error pattern now.)

[kpcwatson]

Additionally, the resolve methods in Container should throw rather than return nil.

[jbradforddillon]

I agree with this as well. I have a branch with makeRequest throwing. @kpcwatson Could you put up a branch with the Container change so we can look at it? That would have some far-reaching effects, but would be fairly simple to ingest.