Modpacks work half the time

[Daltar]

I've been getting back into The Crafting Dead. I played a session just fine yesterday. Then when I tried to open it again last night it would open Minecraft showing the Mojang logo, then close it and open the launcher again as if nothing happened. I played just fine again earlier today but when I tried to open it just now, it doesn't want to work.

Here's my log: https://pastebin.com/JDJmNQ5q

Thanks!