https://pastebin.com/FUtELdxs

When you equip an Elytra, this crash occurs

Does it occur if the other mods installed (e.g. just leaving Quark and AutoRegLib)?

Are you using a cracked client?

Yes.

Try it with a non cracked client then.

That's it, I tested it and it did not crash, but a friend (who crashed) has a cracked client, thx

Yes, same thing: https://pastebin.com/6PcZgJyh