Program: 44417
Project: 44417
Buggy source:
@Override public void onEntityDeath(EntityDeathEvent event){
  if (event.getEntity() instanceof Player) {
    return;
  }
  Player player=null;
  LivingEntity tamedCreature=null;
  if (event.getEntity().getLastDamageCause() instanceof EntityDamageByEntityEvent) {
    EntityDamageByEntityEvent subEvent=(EntityDamageByEntityEvent)event.getEntity().getLastDamageCause();
    if (subEvent.getDamager() instanceof Player) {
      player=(Player)subEvent.getDamager();
    }
 else     if (subEvent.getDamager() instanceof Tameable) {
      if (((Tameable)subEvent.getDamager()).isTamed() && ((Tameable)subEvent.getDamager()).getOwner() instanceof Player) {
        tamedCreature=(LivingEntity)subEvent.getDamager();
        player=(Player)((Tameable)subEvent.getDamager()).getOwner();
      }
    }
 else     if (subEvent.getDamager() instanceof Projectile) {
      if (((Projectile)subEvent.getDamager()).getShooter() instanceof Player) {
        player=(Player)((Projectile)subEvent.getDamager()).getShooter();
      }
    }
  }
  if (player == null) {
    return;
  }
  if (player.getItemInHand().getType().equals(Material.BOW) && !ecoRewardManager.hasBowRewards) {
    plugin.getMessageManager().sendMessage(ecoMessageManager.noBowRewardMessage,player);
    return;
  }
 else   if (ecoEntityUtil.isUnderSeaLevel(player) && !ecoRewardManager.canHuntUnderSeaLevel) {
    plugin.getMessageManager().sendMessage(ecoMessageManager.noBowRewardMessage,player);
    return;
  }
  LivingEntity livingEntity=(LivingEntity)event.getEntity();
  if ((ecoEntityUtil.isNearSpawner(player) || ecoEntityUtil.isNearSpawner(livingEntity)) && !ecoRewardManager.canCampSpawner) {
    if (ecoRewardManager.shouldClearCampDrops) {
      event.getDrops().clear();
    }
    plugin.getMessageManager().sendMessage(ecoMessageManager.noCampMessage,player);
  }
 else {
    plugin.getRewardManager().registerCreatureReward(player,tamedCreature,livingEntity);
  }
  if (ecoRewardManager.rewards.containsKey(livingEntity)) {
    if (ecoRewardManager.shouldOverrideDrops) {
      event.getDrops().clear();
    }
    event.getDrops().addAll(ecoRewardManager.rewards.get(ecoEntityUtil.getCreatureType(livingEntity)).computeDrops());
  }
}

Fixed version (ground truth):
@Override public void onEntityDeath(EntityDeathEvent event){
  if (event.getEntity() instanceof Player) {
    return;
  }
  Player player=null;
  LivingEntity tamedCreature=null;
  if (event.getEntity().getLastDamageCause() instanceof EntityDamageByEntityEvent) {
    EntityDamageByEntityEvent subEvent=(EntityDamageByEntityEvent)event.getEntity().getLastDamageCause();
    if (subEvent.getDamager() instanceof Player) {
      player=(Player)subEvent.getDamager();
    }
 else     if (subEvent.getDamager() instanceof Tameable) {
      if (((Tameable)subEvent.getDamager()).isTamed() && ((Tameable)subEvent.getDamager()).getOwner() instanceof Player) {
        tamedCreature=(LivingEntity)subEvent.getDamager();
        player=(Player)((Tameable)subEvent.getDamager()).getOwner();
      }
    }
 else     if (subEvent.getDamager() instanceof Projectile) {
      if (((Projectile)subEvent.getDamager()).getShooter() instanceof Player) {
        player=(Player)((Projectile)subEvent.getDamager()).getShooter();
      }
    }
  }
  if (player == null) {
    return;
  }
  if (player.getItemInHand().getType().equals(Material.BOW) && !ecoRewardManager.hasBowRewards) {
    plugin.getMessageManager().sendMessage(ecoMessageManager.noBowRewardMessage,player);
    return;
  }
 else   if (ecoEntityUtil.isUnderSeaLevel(player) && !ecoRewardManager.canHuntUnderSeaLevel) {
    plugin.getMessageManager().sendMessage(ecoMessageManager.noBowRewardMessage,player);
    return;
  }
  LivingEntity livingEntity=(LivingEntity)event.getEntity();
  if ((ecoEntityUtil.isNearSpawner(player) || ecoEntityUtil.isNearSpawner(livingEntity)) && !ecoRewardManager.canCampSpawner) {
    if (ecoRewardManager.shouldClearCampDrops) {
      event.getDrops().clear();
    }
    plugin.getMessageManager().sendMessage(ecoMessageManager.noCampMessage,player);
  }
 else {
    plugin.getRewardManager().registerCreatureReward(player,tamedCreature,livingEntity);
  }
  if (ecoRewardManager.rewards.containsKey(ecoEntityUtil.getCreatureType(livingEntity))) {
    if (ecoRewardManager.shouldOverrideDrops) {
      event.getDrops().clear();
    }
    event.getDrops().addAll(ecoRewardManager.rewards.get(ecoEntityUtil.getCreatureType(livingEntity)).computeDrops());
  }
}