Program: 86052
Project: 86052
Buggy source:
@EventHandler public void onPlayerDeath(PlayerDeathEvent event){
  if (pli.global_players.containsKey(event.getEntity().getName())) {
    event.setDeathMessage(null);
    event.getEntity().setHealth(20D);
    final Player p=event.getEntity();
    final Arena arena=pli.global_players.get(p.getName());
    if (arena.getArenaState() == ArenaState.JOIN || (arena.getArenaState() == ArenaState.STARTING && !arena.startedIngameCountdown)) {
      Util.teleportPlayerFixed(p,arena.getWaitingLobbyTemp());
      return;
    }
    arena.global_drops.addAll(event.getDrops());
    arena.spectate(p.getName());
    pli.global_lost.put(p.getName(),pli.global_players.get(p.getName()));
    int count=0;
    for (    String p_ : pli.global_players.keySet()) {
      if (Validator.isPlayerOnline(p_)) {
        if (pli.global_players.get(p_).getInternalName().equalsIgnoreCase(arena.getInternalName())) {
          if (!pli.global_lost.containsKey(p_)) {
            count++;
          }
        }
      }
    }
    final int count_=count;
    Bukkit.getScheduler().runTaskLater(MinigamesAPI.getAPI(),new Runnable(){
      public void run(){
        try {
          if (pli.global_players.containsKey(p.getName()) && count_ > 1) {
            pli.global_players.get(p.getName()).spectate(p.getName());
          }
          for (          String p_ : arena.getAllPlayers()) {
            if (Validator.isPlayerOnline(p_)) {
              Player p__=Bukkit.getPlayer(p_);
              Util.sendMessage(plugin,p__,pli.getMessagesConfig().broadcast_players_left.replaceAll("String_Node_Str",arena.getPlayerCount()));
            }
          }
        }
 catch (        Exception e) {
          e.printStackTrace();
        }
      }
    }
,5);
    if (plugin.getConfig().getBoolean("String_Node_Str")) {
      if (count < 2) {
        arena.stop();
      }
    }
  }
}

Fixed version (ground truth):
@EventHandler(priority=EventPriority.HIGH) public void onPlayerDeath(PlayerDeathEvent event){
  if (pli.global_players.containsKey(event.getEntity().getName())) {
    event.setDeathMessage(null);
    event.getEntity().setHealth(20D);
    final Player p=event.getEntity();
    final Arena arena=pli.global_players.get(p.getName());
    if (arena.getArenaState() == ArenaState.JOIN || (arena.getArenaState() == ArenaState.STARTING && !arena.startedIngameCountdown)) {
      Util.teleportPlayerFixed(p,arena.getWaitingLobbyTemp());
      return;
    }
    arena.global_drops.addAll(event.getDrops());
    arena.spectate(p.getName());
    pli.global_lost.put(p.getName(),pli.global_players.get(p.getName()));
    int count=0;
    for (    String p_ : pli.global_players.keySet()) {
      if (Validator.isPlayerOnline(p_)) {
        if (pli.global_players.get(p_).getInternalName().equalsIgnoreCase(arena.getInternalName())) {
          if (!pli.global_lost.containsKey(p_)) {
            count++;
          }
        }
      }
    }
    final int count_=count;
    Bukkit.getScheduler().runTaskLater(MinigamesAPI.getAPI(),new Runnable(){
      public void run(){
        try {
          if (pli.global_players.containsKey(p.getName()) && count_ > 1) {
            pli.global_players.get(p.getName()).spectate(p.getName());
          }
          for (          String p_ : arena.getAllPlayers()) {
            if (Validator.isPlayerOnline(p_)) {
              Player p__=Bukkit.getPlayer(p_);
              Util.sendMessage(plugin,p__,pli.getMessagesConfig().broadcast_players_left.replaceAll("String_Node_Str",arena.getPlayerCount()));
            }
          }
        }
 catch (        Exception e) {
          e.printStackTrace();
        }
      }
    }
,5);
    if (plugin.getConfig().getBoolean("String_Node_Str")) {
      if (count < 2) {
        arena.stop();
      }
    }
  }
}