spearcore_tensura_compat

SpearCore x Tensura Compat

A small compatibility patch that fixes the launch crash when Spear Core and Tensura: Reincarnated are installed together on NeoForge 1.21.1.

If your game crashes on startup with the error below after adding both mods to your pack, this is the fix.

Critical injection failure: Constant modifier method useItemFirst(F)F
in tensura.mixins.json:client.MixinLocalPlayer

Why the crash happens

When you use an item, Minecraft slows your movement. Both Spear Core and Tensura change that slowdown by editing the same constants inside LocalPlayer.aiStep:

• Spear Core 3.1.0 does it in LocalPlayerInputMixin, so spears can be used without the normal slowdown.
• Tensura 2.0.1.3 does it in client.MixinLocalPlayer, through its useItemFirst and useItemSecond injectors.

Mixin only lets one mod change a given constant. It skips Tensura’s injector as a conflict, and because that injector is required, the game stops with an InjectionError before the main menu.