With AS version 1.10.11, on a server running forge-1.12.2-14.23.5.2814, when I open up an augmented sextant (where I look doesn't matter) the server crashes seconds later without a crash log. I haven't tested this on single player yet.

Going to need a log of some sort to do anything about this.

I'd also recommend updating to 1.10.13.

Did adjust some things serversided regarding this.
Update to 1.10.14 and test this again.

@RandomSomething98 any update?

So I've been able to utilize the sextant a little bit on the latest update, but it still mysteriously crashes. One thing I have noticed is that the times it has crashed I pressed shift quickly to get to the selections on the right, but the crash would interrupt that process. I looked into my server logs and my start.sh file literally just restarts, theres no error or indication of what caused it. Could this be caused by what's on the JVM arguments in my start.sh conflicting with Astral Sorcery? I'll post the start.sh file here: https://pastebin.com/Pf7rrigC

Anything in the os event logs?

Sorry, the server is on a VPS running Debian, and I can't find the OS event logs.

I meant from your workstation, the client

@RandomSomething98 can you try the latest AS release (1.17) and let us know if still happening? Client log when it happens would be good.

Sorry for the wait. I've updated to forge version 2836 and the 1.17 version Astral Sorcery.
I've been able to replicate this error by spawning in the world then using the sextant within the first 10 seconds or so I'm in. I've looked into it client side, and found this comment in my latest.log:

[14:11:00] [Client thread/INFO] [foamfix]: Unloaded world <net.minecraft.client.multiplayer.WorldClient@4a4ddb12 0 MultiplayerChunkCache: 441, 441> is still hanging around after 60 seconds.
[14:11:00] [Client thread/INFO] [foamfix]: This may be due to a world leak, or there is little memory pressure.
[14:11:00] [Client thread/INFO] [foamfix]: Use the relevant FoamFix options to adjust the wait time.
[14:11:44] [Client thread/INFO] [foamfix]: Unloaded world

So I think this may just be a foamfix issue. Googling this tells me that perhaps my server or client isn't beefy enough (I'm running a custom modpack with 53 mods on 2 gigs).
In trying to replicate this, I came across a new crash. server side when using the sextant like before, which I have linked here: https://pastebin.com/MbF9sAZd

EDIT:
Seems like the foamfix message only happened that one time. I'm back to the drawing board, as neither the client or the server are giving any details to the original error that crashes the server.