Design nicer error/placeholder pages #596
Description
Remaining from #118:
- Error page designs (404.html, 500.html)
- Design and handle error messages for empty sections
- Discussion list (e.g. search, see When searching for something with few characters doesn't throw error. issue-archive#368 773)
- User profile: Activity
- User profile: Mentions (see Blank screen if no mentions are available on the mentions tab (profile) #1489)
- more?
- Design and handle error page for discussion not found, user not found, route not found, etc.