bloodmoon+thaumcraft error.txt
From what I have been studying the error is caused when Bloodmoon shading tries to affect the thaumcraft particles (Flux clouds especially, not sure about the flux rifts yet) causing the client to crash.
The bloodmoon and thaumcraft 6 both work fine when all the shaders are disabled from bloodmoon.
P.S. If possible, could you add customizable messages on events such as Bloodmoon starting, ending and being stopped.

Not exactly a crash but I got a "Network Disconnect: A fatal error has occurred, this connection is terminated" error.

Log:
https://pastebin.com/jifzPb1N

Mods: 4
Baubles-1.12-1.5.2
Bloodmoon-MC1.12.2-1.5.3
jei_1.12.2-4.15.0.291
Thaumcraft-1.12.2-6.1.BETA26

As Nipde said, only way to avoid getting booted out is to set all appearance options to false in the Bloodmoon config.

How to do:
Get a Flux Geyser from somewhere and then place them somewhere... in due time they'll turn into flux goo, now either wait for a Bloodmoon or force it via commands and then wait near the flux goo... in due time... you'll get booted out of the game.