Doesn't work with subscriptions properly

[DmitryVlaznev]

When I use apollo-link-state and a client-only field with a @client directive which is mixed with subscription data as described here (a value actually comes from state link defaults), apollo-link-state unsubscribes a subscription silently after the first response.

I found the following code into the index.ts file:

.then(nextData => {
  observer.next({
    data: nextData,
    errors,
  });
  observer.complete();
})

apollo-link-state/packages/apollo-link-state/src/index.ts

Line 109 in 404b6a1

observer.complete();

When I replaced this code with the followed one

.then(nextData => {
  observer.next({
    data: nextData,
    errors,
  });
  if (type !== 'Subscription') {
    observer.complete();
  }
})

a subscription starts working as expected.

[DmitryVlaznev]

I tried to use this patch above (built a package from a master branch) but got an error:

TypeError: obs.flatMap is not a function

I've realized that it is more than likely that one of the links in the links chain returns ObservableLike object instead of an Observable.

[hwillson]

Related to #138.