suspected incompatability with guarding mod, shield changes appear to conflict with changes from guarding mod, causes a crash during loading.

[00:14:37] [main/WARN]: @ModifyConstant conflict. Skipping guarding.mixins.json:LivingEntityMixin from mod guarding->@ModifyConstant::removeShieldDelay(I)I with priority 1000, already redirected by cenchants.mixins.json:CenchantsLivingEntityMixin from mod cenchants->@ModifyConstant::modifyArmTime(I)I with priority 1000
[00:14:37] [main/ERROR]: Minecraft has crashed!

fixed in issue #26 already, use a newer version