This commit includes several pieces of functionality to enable services
to be removed and the page to present information that this has happened
but also keep the deleted information on the page. Along with the more
usual blocking query based listing.
To enable this:
1. Implements `meta` on the model (only available on collections in
ember)
2. Adds new `catchable` ComputedProperty alongside a `listen` helper for
working with specific errors that can be thrown from EventSources in an
ember-like way. Briefly, normal computed properties update when a
property changes, EventSources can additionally throw errors so we can
catch them and show different visuals based on that.
Also:
Add support for blocking queries on the service instance detail page
1. Previous we could return undefined when a service instance has no
proxy, but this means we have nothing to attach `meta` to. We've changed
this to return an almost empty object, so with only a meta property.
At first glance there doesn't seem to be any way to provide a proxy
object to templates and be able to detect whether it is actually null
or not so we instead change some conditional logic in the templates to
detect the property we are using to generate the anchor.
2. Made a `pauseUntil` test helper function for steps where we wait for
things. This helps for DRYness but also means if we can move away from
setInterval to something else later, we can do it in one place
3. Whilst running into point 1 here, we managed to make the blocking
queries eternally loop. Whilst this is due to an error in the code and
shouldn't ever happen whilst in actual use, we've added an extra check
so that we only recur/loop the blocking query if the previous response has a
`meta.cursor`
Adds support for blocking queries on the node detail page (#5489)
1. Moves data re-shaping for the templates variables into a repository
so they are easily covered by blocking queries (into coordinatesRepo)
2. The node API returns a 404 as signal for deregistration, we also
close the sessions and coordinates blocking queries when this happens