Moving an Iron dropper with a piston crashes games / servers

[WhyCantPigsFly]

Modpack version
1.71

Issue
If you use a sticky piston to move an iron dropper (maybe others, but this is the only one I've tried), your game / server will freeze and eventually crash.

Logs
https://pastebin.com/PKKkxTzc

[NielsPilgaard]

Thanks for the report, I blacklisted all Random Things blocks from being moved by pistons.