Problem Details

• Right-clicking Cyclic's Stone Minecart onto a track crashes the game, while the gold minecart doesn't cause a crash.
• Crash Log

Environment

• OS: Windows 10, Java 1.8.0_51 64 bit
• Full Forge version: v14.23.5.2838
• Metal Transport version: v2.0.6
• Cyclic v1.19.12

Have you whitelisted any of Cyclic's cart classes in the config file?

No, I haven't.
I'm not even sure how to do that.