Game Crashes On Start-Up 1.16.5

[lavaking993]

game crashes on start up randomly

https://pastebin.com/qfj2wpBP
(Behold The Sanctum Modpack)

[ZacSharp]

This crash is MixinIntegratedServer from Essential failing. Litematica also has a mixin for IntegratedServer so this could be an unusual kind of mixin conflict. (Also am I correct assuming Essential is from essential.gg and the modpack is https://www.curseforge.com/minecraft/modpacks/behold-the-sanctum?)
Could you maybe try whether just Essential is enough to cause the crash? Also might be worth reporting this to Essential as well, though they don't seem to have a bug tracker, just a support discord.