Basically, Lemmy has some bug that caused the process to have a spike in memory. This spike caused the limits I had in place to make lemmy restart. Thus the server was actually down for the tiny period when you saw these.
Fortunately since (checks time) 3 hours ago, that has completely solved. We've doubled our memory on our server and we have had memory spikes, but it hasn't caused Lemmy to stop processing requests.
The actual error is the Lemmy user interface expecting a valid response, and it getting an error. This error can also happen if you attempt to upload an image and the upload fails for some reason.
All in all, it should be back to normal, and operating as fast as possible.