Program: 1827
Project: 1827
Buggy source:
@Override public void run(){
  for (  Entry<Integer,HumanNPC> entry : NPCManager.getList().entrySet()) {
    HumanNPC npc=entry.getValue();
    if (npc.isType("String_Node_Str")) {
      Guard guard=npc.getType("String_Node_Str");
      if (guard.isAttacking() && !npc.getHandle().hasTarget()) {
        GuardManager.returnToBase(guard,npc);
        guard.setAttacking(false);
      }
      if (guard.isAttacking() && npc.getHandle().hasTarget() && (!LocationUtils.withinRange(npc.getLocation(),npc.getHandle().getTarget().getLocation(),guard.getProtectionRadius()) || !LocationUtils.withinRange(npc.getLocation(),npc.getNPCData().getLocation(),guard.getProtectionRadius()))) {
        npc.getHandle().cancelTarget();
        GuardManager.returnToBase(guard,npc);
        guard.setAttacking(false);
      }
      if (guard.isAttacking()) {
        continue;
      }
      if (npc.isPaused() && LocationUtils.withinRange(npc.getLocation(),npc.getNPCData().getLocation())) {
        npc.setPaused(false);
      }
      if (guard.isBouncer()) {
        handleTarget(npc.getPlayer(),npc,guard);
      }
 else       if (guard.isBodyguard()) {
        if (!npc.isPaused()) {
          npc.setPaused(true);
        }
        Player p=Bukkit.getServer().getPlayer(npc.getOwner());
        if (p != null) {
          handleTarget(p,npc,guard);
          if (LocationUtils.withinRange(npc.getLocation(),p.getLocation(),25)) {
            PathUtils.target(npc,p,false,-1,-1,25);
          }
 else {
            npc.teleport(p.getLocation());
          }
        }
 else {
          if (NPCManager.get(npc.getUID()) != null) {
            toRespawn.put(npc.getOwner(),new NPCLocation(npc.getLocation(),npc.getUID(),npc.getOwner()));
            NPCManager.despawn(npc.getUID());
          }
        }
      }
    }
  }
}

Fixed version (ground truth):
@Override public void run(){
  for (  Entry<Integer,HumanNPC> entry : NPCManager.getList().entrySet()) {
    HumanNPC npc=entry.getValue();
    if (npc.isType("String_Node_Str")) {
      Guard guard=npc.getType("String_Node_Str");
      if (guard.isAttacking() && !npc.getHandle().hasTarget()) {
        GuardManager.returnToBase(guard,npc);
        guard.setAttacking(false);
      }
      if (guard.isAttacking() && npc.getHandle().hasTarget() && (!LocationUtils.withinRange(npc.getLocation(),npc.getHandle().getTarget().getLocation(),guard.getProtectionRadius()))) {
        npc.getHandle().cancelTarget();
        GuardManager.returnToBase(guard,npc);
        guard.setAttacking(false);
      }
      if (guard.isAttacking()) {
        continue;
      }
      if (npc.isPaused() && LocationUtils.withinRange(npc.getLocation(),npc.getNPCData().getLocation())) {
        npc.setPaused(false);
      }
      if (guard.isBouncer()) {
        handleTarget(npc.getPlayer(),npc,guard);
      }
 else       if (guard.isBodyguard()) {
        if (!npc.isPaused()) {
          npc.setPaused(true);
        }
        Player p=Bukkit.getServer().getPlayer(npc.getOwner());
        if (p != null) {
          handleTarget(p,npc,guard);
          if (LocationUtils.withinRange(npc.getLocation(),p.getLocation(),25)) {
            PathUtils.target(npc,p,false,-1,-1,25);
          }
 else {
            npc.teleport(p.getLocation());
          }
        }
 else {
          if (NPCManager.get(npc.getUID()) != null) {
            toRespawn.put(npc.getOwner(),new NPCLocation(npc.getLocation(),npc.getUID(),npc.getOwner()));
            NPCManager.despawn(npc.getUID());
          }
        }
      }
    }
  }
}