Geckolib custom attack animations cause compile errors.

Yes, it was.

For any future people that might happen to get this error:

Lock the entity so you can edit the code.

find this part of the code in the (Your mob)Entity.java:

if (getAttackAnim(event.getPartialTick()) > 0f && !this.swinging) {

            this.swinging = true;

            this.lastSwing = level.getGameTime();

        }

        if (this.swinging && this.lastSwing + 7L <= level.getGameTime()) {

            this.swinging = false;

And switch BOTH level.getGameTime() to level().getGameTime()

It should look like this:

if (getAttackAnim(event.getPartialTick()) > 0f && !this.swinging) {

            this.swinging = true;

            this.lastSwing = level().getGameTime();

        }

        if (this.swinging && this.lastSwing + 7L <= level().getGameTime()) {

            this.swinging = false;