Comments from the previously viewed post linger until comments from the current post load

[redcathode]

** Jerboa Version **
0.0.33

Describe the bug
While the comments on a post are still loading, Jerboa shows the comments from the last-viewed post as if they were on the current post. Additionally, if the comments from the current post fail to load, Jerboa seems to happily display the wrong comment section without showing an error.

This doesn't necessarily make the app less usable, but it's really confusing for new users and might lead to people with slow or patchy internet commenting on the wrong post, so adding some sort of "Comments Loading" bit should be a somewhat high priority.

To Reproduce
Steps to reproduce the behavior:

1. Open a post and wait for the comments to load
2. Close the post, open another one, and quickly scroll down to the comments
3. While the loading bar is still present (or if the new comments fail to load), Jerboa displays the comments from the previous post

[redcathode]

This also happens with posts in communities