FabInjector failed to find injection point for net/minecraft/client/player/LocalPlayer;m_8107_()V Lnet/minecraft/client/KeyMapping;m_90857_()Z
located in com.unascribed.fabrication.mixin.b_utility.toggle_sprint.MixinClientPlayerEntity

nvm it wasnt your mod but still this part^

At the time i was trying to use better combat which seems to be the cause of the crash. After disabling it, your mode works fine and I do not seem to get that message

Im not sure how to do what you mentioned

if you're using the vanilla launcher you click launch options, turn on advanced settings, turn on JVM arguments, add -Dmixin.debug.export=true to the args which will export the class to the before mentioned path.

i'd need the mixin export to make sure, but i'm assuming some other mod modifies the same bit of the game. making the injection fail and toggle_sprint getting turned off (it shouldn't crash though, correct me if it does)

i'd like to find out what mod is causing it, to have something to test with when i get around to it. could you please add -Dmixin.debug.export=true to the java args, launch the game and send over .minecraft/.mixin.out/class/net/minecraft/client/player/LocalPlayer.class

the other way to check what mod causes it would be to add/remove mods untill toggle sprint doesn't show up when you type #failed into the UIs feature search.

that takes a bit though and this is probably fixed in 3.2.1 anyway