setup screen is displayed when there is an error connecting to the API

[good-idea]

I discovered this after updating the URL in use from https://your-storefront-name.myshopify.com/api/graphql to /api/2020-01/graphql. According to the shopify docs, this should work, but it doesn't. Anyway, it shows the Setup screen instead of a displaying some kind of error about connecting to the API:

A request with a bad token will also return an error - so, we'll need to differentiate between that error and other that are just not connecting in the first place, either because the URL is somehow bad (maybe the storefront name changed, but it hasn't been updated in sanity), or the request is somehow blocked in another way.