[Reader] Discover tab empty while loading for the first time

[thomashorta]

ref: p5T066-47C-p2#comment-14973

Expected Behavior

When installing/logging into the app for the first time and going to the Reader Discover tab, the posts list should just show a loading state while loading.

Actual Behavior

When installing/logging into the app for the first time and going to the Reader Discover tab, the posts list is replaced with an "Empty" state that says there are no posts available.

Steps to reproduce

1. Fresh install the app
2. Login to an account that follows some sites/tags
3. Navigate to the reader tab
4. ⚠️ Notice that for the moment it shows that there are no posts and prompts the user to follow topics