The crash was caused by MixinMinecraft#<init> not being inserted when some other mods mixin in a similar place, but I am not entirely sure why the Mixin system wasn't inserting it. Whatever it may be, it works now and has the added benefit of showing ViaForge in the mods list.
The crash was caused by MixinMinecraft#<init> not being inserted when some other mods mixin in a similar place, but I am not entirely sure why the Mixin system wasn't inserting it. Whatever it may be, it works now and has the added benefit of showing ViaForge in the mods list.