To Reproduce
Steps to reproduce the crash:

1. Open Minecraft
2. Create Creative World
3. Place any WWII vehicle
4. Look sad as your game crashes

• Forge: 1.12.2 latest
• Flan's Mod: 5.6 beta 10 for 1.12.2

In the middle of making a modpack and wanted to add the flans mod.
crash-2021-12-20_16.21.52-server.txt
Got flans mod straight from the github because I looked at all the other crashes that were similar to mine.

My Bad!
First time using the flans mod and completely forgot the simple parts content pack.