Program: 31501
Project: 31501
Buggy source:
@Inject(method="String_Node_Str",at=@At("String_Node_Str"),cancellable=true) private void callDestructEntityEventDeath(DamageSource source,CallbackInfo ci){
  MessageSink messageSink=this instanceof Player ? ((Player)this).getMessageSink() : MessageSinks.toNone();
  Text deathMessage=SpongeTexts.toText(getCombatTracker().getDeathMessage());
  Optional<User> sourceCreator=Optional.empty();
  Cause cause;
  if (source instanceof EntityDamageSource) {
    EntityDamageSource damageSource=(EntityDamageSource)source;
    IMixinEntity spongeEntity=(IMixinEntity)damageSource.getSourceOfDamage();
    sourceCreator=spongeEntity.getTrackedPlayer(NbtDataUtil.SPONGE_ENTITY_CREATOR);
  }
  if (sourceCreator.isPresent()) {
    cause=Cause.of(NamedCause.source(source),NamedCause.of("String_Node_Str",this),NamedCause.owner(sourceCreator.get()));
  }
 else {
    cause=Cause.of(NamedCause.source(source),NamedCause.of("String_Node_Str",this));
  }
  DestructEntityEvent.Death event=SpongeEventFactory.createDestructEntityEventDeath(SpongeImpl.getGame(),cause,deathMessage,deathMessage,messageSink,messageSink,(Living)this);
  if (!SpongeImpl.postEvent(event)) {
    deathMessage=event.getMessage();
    if (deathMessage != Texts.of()) {
      event.getSink().sendMessage(deathMessage);
    }
    if (sourceCreator.isPresent()) {
      StaticMixinHelper.dropCause=Cause.of(NamedCause.source(this),NamedCause.of("String_Node_Str",source),NamedCause.owner(sourceCreator.get()));
    }
 else {
      StaticMixinHelper.dropCause=Cause.of(NamedCause.source(this),NamedCause.of("String_Node_Str",source));
    }
  }
 else {
    ci.cancel();
  }
}

Fixed version (ground truth):
private void callDestructEntityEventDeath(DamageSource source,CallbackInfo ci){
  MessageSink messageSink=this instanceof Player ? ((Player)this).getMessageSink() : MessageSinks.toNone();
  Text deathMessage=SpongeTexts.toText(getCombatTracker().getDeathMessage());
  Optional<User> sourceCreator=Optional.empty();
  Cause cause;
  if (source instanceof EntityDamageSource) {
    EntityDamageSource damageSource=(EntityDamageSource)source;
    IMixinEntity spongeEntity=(IMixinEntity)damageSource.getSourceOfDamage();
    sourceCreator=spongeEntity.getTrackedPlayer(NbtDataUtil.SPONGE_ENTITY_CREATOR);
  }
  if (sourceCreator.isPresent()) {
    cause=Cause.of(NamedCause.source(source),NamedCause.of("String_Node_Str",this),NamedCause.owner(sourceCreator.get()));
  }
 else {
    cause=Cause.of(NamedCause.source(source),NamedCause.of("String_Node_Str",this));
  }
  DestructEntityEvent.Death event=SpongeEventFactory.createDestructEntityEventDeath(SpongeImpl.getGame(),cause,deathMessage,deathMessage,messageSink,messageSink,(Living)this);
  if (!SpongeImpl.postEvent(event)) {
    deathMessage=event.getMessage();
    if (deathMessage != Texts.of()) {
      event.getSink().sendMessage(deathMessage);
    }
    if (sourceCreator.isPresent()) {
      StaticMixinHelper.dropCause=Cause.of(NamedCause.source(this),NamedCause.of("String_Node_Str",source),NamedCause.owner(sourceCreator.get()));
    }
 else {
      StaticMixinHelper.dropCause=Cause.of(NamedCause.source(this),NamedCause.of("String_Node_Str",source));
    }
  }
 else {
    ci.cancel();
  }
}