I am trying to make an addon for MrCrayfish's Gun Mod. There are no tutorials anywhere so I've relied on existing addons for reference. Whenever I try and run Minecraft, the gun mod throws this error:

org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException: Critical injection failure: @Inject annotation on capture could not find any targets matching 'Lnet/minecraft/world/entity/LivingEntity;m_6469_(Lnet/minecraft/world/damagesource/DamageSource;F)Z' in net.minecraft.world.entity.LivingEntity. Using refmap cgm.refmap.json [PREINJECT Applicator Phase -> cgm.mixins.json:common.LivingEntityMixin -> Prepare Injections -> -> handler$zzb000$capture(Lnet/minecraft/world/damagesource/DamageSource;FLorg/spongepowered/asm/mixin/injection/callback/CallbackInfoReturnable;)V -> Parse]

When I compile my addon and run it in normal Minecraft, it works perfectly. I'm not sure how to fix it.

I am having the same issue with IntelliJ IDEA, trying to test compatibility with my mod. The culprit seems to be Framework though, when I remove it the game loads fine.
Have you gotten any further? I'm not sure I'm just missing out on something obvious...

I have not made any progress. I ended up using this cycle: changing my mod, compiling my mod, then running it in actual Minecraft to test it. It definitely took longer, but at least it worked. If you can't fix the problem either, then this is the only solution I have for you.