The game crashed whilst initializing game
Error: java.lang.NoClassDefFoundError: net/minecraft/client/renderer/EntityRenderer

version : 1.12.2

Other mods used :

Additional Structures

AI Improvements

AutoRegLib

Better Foliage

BetterFps

BetterPortals

Bloodmoon

BloodmoonCMSFix (BMCMSFix)

CoroUtil

CreativeCore

Custom Mob Spawner

Day Zombies

Doomlike Dungeons

Durability Mod

Dynamic Surroundings

Dynamic Trees

Dynamic Trees - Biomes O' Plenty

Familiar Fauna

iChunUtil

Just Enough Items (JEI)

Lost Souls

Macaw's Bridges

MixinBootstrap

Mob Dismemberment

Mouse Tweaks

OreLib

Quark

Roguelike Dungeons -- Fnar's Edition

Scape and Run: Parasites

Shadowfacts' Forgelin

Spartan Shields

Spartan Weaponry

SwingThroughGrass

The Lost Cities

Wolf Armor and Storage Legacy

Zombie Awareness

So, any library mod can make this one not work? That's not cool (also seems to not work with any mod that changes visuals/noise because the portals mod uses vanilla aspects that break whenever other mods use it, but I don't know anything about java so I have no clue what I'm talking about)

Disable mods until it stops happening, then test with only Better Portals and the mod that seems to be causing your issue.

I had this issue a while back and Dynamic Surroundings was the issue.
I have no idea why, I'm not versed in java, but they conflict for some reason.

ShadowMC caused it for me