Crash on .unwrap for instances under heavy load

[CMahaff]

Describe the Bug
Lemmy has a behavior, IMO a bug, where when under heavy load the /api/v3/site will start returning data as if the user is logged out, even if they are logged in. This causes LASIM to crash since it expects that user data to be present, and that data is required to do anything useful.

Change LASIM to report an error in this condition instead.

Information
LASIM Version: 0.2.1
LASIM Profile Version: 2
Lemmy Source Instance URL: N/A
Lemmy Source Instance Version: N/A
Lemmy Target Instance URL: N/A
Lemmy Target Instance Version: N/A

Output of LASIM
N/A