Reference: AllTheMods/ATM-6#1332

Industrial Foregoing Version: industrial-foregoing-1.16.5-3.2.11-55cb112

Titanium Version: titanium-1.16.5-3.2.8.2

Crashlog: https://pastebin.com/BY98BCfk

Same issue here. Inserted a Firework rocket [Large ball + White + Twinkle + Trail] with Flight duration 1. The server crashed right away. Playing the Enigmatica 6 modpack, version 0.4.8.

Adding my crash report in case it helps:
crash-2021-04-12_07.26.30-server.txt