Issue description:
Server is crashing during launch.
If crashed, link to crash report (use a site such as pastebin):
Crash-report: https://ghostbin.co/paste/ujvuyd

Versions:

• Minecraft: 1.16.5
• Forge: 36.1.16
• Mantle: 1.6.92
• Tinkers Construct: 3.0.3.132 (test 3.0.3135 also)
  Version 3.0.3.131 is still working fine.

Confirm below that this issue is not covered on the roadmap or "Whats New?"
Confirmed
Can it be reproduced with just Tinkers Construct? If not, list the other mods required to reproduce the issue.
Yes, see crash-report, please.