https://pastebin.com/H1dsqETW

mods present: astral sorcery, crafttweaker, gamestages, itemstages, chisel (as example);
one line mods.ItemStages.stageModItems("chisel", "chisel"); makes AS spew out an NPE and create a crashlog, and somehow breaks progressing through AS;
this behaviour only seems to occur on AS versions after 1.10.4, where AS' internal gamestage support was added

Same issue. Reverting to 1.10.3 for now.
https://paste.dimdev.org/delevunuqi.mccrash

Some additional info:

• Survival multiplayer server
• Beds don't let the player sleep properly, but using them sometimes successfully advances the night
• Player head seemed to be missing the floaty texture layer**, but helmets and such worked fine
• One player (could be isolated) could log in, but immediately de-synced (couldn't place blocks or interact with entities). After relogging, he would be in the same spot, as if he never moved

** - Pretty sure this is the correct technical term for the layer of textures drawn over the base textures, such as for layered clothing effects

Not connected to whatever you reported there btw.