Sync latest code from Sapper

[benmccann]

E.g. compare https://github.com/sveltejs/kit/tree/master/packages/kit/src/client vs https://github.com/sveltejs/sapper/tree/master/runtime/src/app

We'll have to come up with a strategy for this because there have been a lot of fixes and improvements recently. I can slow down on merging Sapper stuff if it makes it easier to manage

[Rich-Harris]

I've copied over all the router code — is there anything else you can think of? If not, we can close this issue

[benmccann]

@ehrencrona you might want to check if sveltejs/sapper#1498 got ported over to Kit. I tried looking, but the page store type is still TODO, so I wasn't sure:

kit/packages/kit/src/runtime/stores/index.ts

Line 7 in 8e5d91b

page: any // TODO

sveltejs/sapper#1569 might be a good one to check as well

[Rich-Harris]

pretty sure we can close this now, i'm sure we'll find out in due course if not

[benmccann]

I think we almost have all of this done. The one I think we haven't yet is sveltejs/sapper#1498 - store the current error in the page store to allow the layout to know whether the current page is an error page

[Rich-Harris]

Given that it only applies to the root layout I think I'd prefer that we pass the error (and possibly status) as a prop. It doesn't belong on the page store

[benmccann]

Ok. Created a separate issue for that (#598) and will close this