The only relevant part from java crash dump is:
RSI={method} {0x00000000005b5680} 'renderTargets' '(F)V' in 'hellfirepvp/astralsorcery/client/util/UISextantTarget'

Java version: 1.8.0_u181 (64 bit).
Modpack: FTB Relevation 2.5.0.
Mod version: astralsorcery-1.12.2-1.9.4.jar.

Error occured while flying in Creative mode around NPC village at night.

Full log: https://paste.dimdev.org/ipalibepol.makefile

P.S. Access token changed. Didn't know Java dumps so much.

Because there is nothing what would help you in client log – https://paste.dimdev.org/eriyukazej.md.

So...why is java failing to map something to memory and java crashing an AS issue?

Because there are ways to perform tasks without engine failing and there are ways to perform tasks so you would blame engine for crashes.

...why would you post a java dump? We don't code correct java.

Full client log, please.