1.19.2 Psi 2.0.0
I started crashing or disconnecting me(i mean the Mc shoves me to multiplayer menu saying disconected instead of crash) when using my cad flight spell ( https://imgur.com/a/Y7MEhQt )
and when i disabled mod Observable 3.3.1 it stopped
2024-03-27-2.log.gz
crash-2024-03-27_18.55.08-fml.txt
and it doesnt happen imidiatly usually after aproximately 1s up to several minutes (in case i did'nt i send the correct log and crash files tell me)

Try to update forge.
They changed something essential in the 1.19 development cycle(it seems to be around forge 4.3.1 or 4.3.2). It crashes when the version with which the mod was compiled and your are using are before and after the change. If both are before or both are after the change it works but if you are mixing them, it crashes.
Kotlin for Forge 3.7.1 added a check to patch incompatible mods.
I wrote to the developers of the Essential Mod but I don't know how long it will take to fix it or if there will effer do it.

Ok, normalie forge figure it out itself but Essential does some pretty weird stuff and doesn't load it true forge so there might be some instances were the wrong version is used.

TheThe crash from the log is caused by an old version of Kotlin for Forge. It's probably bundelt with some mod so it might not be in your mod folder. The current version is 3.12.0 just drop it in your mod folder and it should work.
I don't know if it is the bug you're currently experiencing because for me it's crashing while loading minecraft but it's creating the same crashlog you posted.

Well, that's interesting inconsistency.
Not sure if disabling observable just makes it take lot longer to crash but how can I check which mods could be using/has the outdated kotlin? So this report is more precise if anyone finds it.

The old version is bundled with the “Essential Mod” but it should only load when no other version of “Kotlin for Forge” is loaded. So you should be able to just drop a more recent version of it into your mod folder and it should work.

i tried updating essentials and i had kotlin 3.12.0 and it still closes my world when flying
crash-2024-06-28_11.43.17-client.txt
(after i checked i did update my forge but it still happens)
(now i tried disabling inventorio and havent crashed yet but also observable refused to load and didnt say why)

Also apparently i am not the only one who crashes with flying type things i found crash related to not having kotlin with jetpack so i dont think i chose the right mod. (the psi spell acts like kinda inacurate jetpack) downgraded kotlin to one from febuary 3100