[1.20.1] Cannot load or create world with Elytra Trims + Upgrade Aquatic

[Diamondback88]

Mod loader

Forge

Minecraft version

1.20.1

Mod version

3.5.2

Affected mods

• Elytra Trims
• Extensions

Bug description

When attempting to load a world with Blueprint, Elytra Trims, Kotlin for Forge, and Upgrade Aquatic on recommended Forge version 47.1.3, the world will refuse to launch and only offer a "safe mode" option to launch the world. If you attempt to create a new world, the game will crash.

It's worth noting that this also happens on the latest NeoForge version for 1.20.1 (47.1.106); this is likely because this NeoForge version has parity with Forge version 47.1.3.

Steps to reproduce

1. Install Blueprint, Elytra Trims, Kotlin for Forge, and Upgrade Aquatic.
2. Load an existing world.
3. Receive the error.

OR:

1. Install Blueprint, Elytra Trims, Kotlin for Forge, and Upgrade Aquatic.
2. Attempt to create a new world.
3. The game will crash.

Relevant logs

https://mclo.gs/XHW4wIF

[mkern1200]

I'm encountering this issue as well, same mod version and environment. I don't have Blueprint or Update Aquatic installed, but every time I try to create a world the game immediately crashes. Crash log below for reference (sorry, I wasn't able to isolate which other mod(s) it's conflicting with, so it's a long list):
crash-2024-09-16_22.54.33-client.txt