@mattwr18 vue-apollo rocks! Taking the time to study the docs is a
rewarding investment.
My first idea was to cache the `unreadNotificationsCount` with Vuex.
But the docs of apollo even suggest to use apollo's local state as a
complete replacement of Vuex:
https://vue-apollo.netlify.com/guide/local-state.html
Then I further investigated why the updated `NOTIFIED` objects won't
update the notification counter. Turns out: They don't have an ID and
the computed property didn't fire when the notifications array would
change. I fixed both in this commit and yes, it works as expected.
No additional code required 💪
