Vue-apollo: $apollo undefined in SSR

[dsanders11]

Describe the bug
After c3b840c368d50cb21f7410119a50443596baa537, any usage of $apollo (such as $apollo.queries.<query>.loading) in templates will result in an error. This is because $apollo will now be null.

@Akryum, is it possible to retain the memory leak fix in c3b840c368d50cb21f7410119a50443596baa537 by only destroying $apollo, without it being set to null?

Versions
vue: 2.6.10
vue-apollo: 3.0.0

[sebmor]

+1 Came here to post exactly this

[Akryum]

Test: https://github.com/vuejs/vue-apollo/blob/81b8a4894ab3ebf84f2de030f290604e1e7c26c7/packages/test-ssr/tests/e2e/specs/apollo-ssr.js#L13-L17