Program: 38770
Project: 38770
Buggy source:
@EventHandler public void playerPortal(PlayerPortalEvent event){
  this.plugin.log(Level.FINER,"String_Node_Str");
  PortalManager pm=this.plugin.getPortalManager();
  MVPortal portal=pm.isPortal(event.getPlayer(),event.getPlayer().getLocation());
  if (portal == null) {
    Location newLoc=SafeTTeleporter.findPortalBlockNextTo(event.getFrom());
    if (newLoc != null) {
      this.plugin.log(Level.FINER,"String_Node_Str");
      portal=pm.isPortal(event.getPlayer(),newLoc);
    }
  }
  if (portal != null) {
    this.plugin.log(Level.FINER,"String_Node_Str");
    MVDestination portalDest=portal.getDestination();
    if (portalDest != null && !(portalDest instanceof InvalidDestination)) {
      PortalPlayerSession ps=this.plugin.getPortalSession(event.getPlayer());
      if (!ps.allowTeleportViaCooldown(new Date())) {
        event.getPlayer().sendMessage(ps.getFriendlyRemainingTimeMessage());
        event.setCancelled(true);
        return;
      }
      TravelAgent agent=new MVTravelAgent(this.plugin.getCore(),portalDest,event.getPlayer());
      event.setTo(portalDest.getLocation(event.getPlayer()));
      if (portalDest.useSafeTeleporter()) {
        SafeTTeleporter teleporter=this.plugin.getCore().getTeleporter();
        event.setTo(teleporter.getSafeLocation(event.getPlayer(),portalDest));
      }
      event.setPortalTravelAgent(agent);
      event.useTravelAgent(true);
      MVPortalEvent portalEvent=new MVPortalEvent(portalDest,event.getPlayer(),agent);
      this.plugin.getServer().getPluginManager().callEvent(portalEvent);
      if (portalEvent.isCancelled()) {
        event.setCancelled(true);
        this.plugin.log(Level.FINE,"String_Node_Str");
        return;
      }
      this.plugin.log(Level.FINE,"String_Node_Str");
    }
 else     if (!this.plugin.getMainConfig().getBoolean("String_Node_Str",false)) {
      event.getPlayer().sendMessage("String_Node_Str" + ChatColor.RED + "String_Node_Str"+ ChatColor.RED+ "String_Node_Str");
      event.setCancelled(true);
    }
  }
}

Fixed version (ground truth):
@EventHandler public void playerPortal(PlayerPortalEvent event){
  this.plugin.log(Level.FINER,"String_Node_Str");
  PortalManager pm=this.plugin.getPortalManager();
  MVPortal portal=pm.isPortal(event.getPlayer(),event.getPlayer().getLocation());
  if (portal == null) {
    Location newLoc=this.plugin.getCore().getSafeTTeleporter().findPortalBlockNextTo(event.getFrom());
    if (newLoc != null) {
      this.plugin.log(Level.FINER,"String_Node_Str");
      portal=pm.isPortal(event.getPlayer(),newLoc);
    }
  }
  if (portal != null) {
    this.plugin.log(Level.FINER,"String_Node_Str");
    MVDestination portalDest=portal.getDestination();
    if (portalDest != null && !(portalDest instanceof InvalidDestination)) {
      PortalPlayerSession ps=this.plugin.getPortalSession(event.getPlayer());
      if (!ps.allowTeleportViaCooldown(new Date())) {
        event.getPlayer().sendMessage(ps.getFriendlyRemainingTimeMessage());
        event.setCancelled(true);
        return;
      }
      TravelAgent agent=new MVTravelAgent(this.plugin.getCore(),portalDest,event.getPlayer());
      event.setTo(portalDest.getLocation(event.getPlayer()));
      if (portalDest.useSafeTeleporter()) {
        SafeTTeleporter teleporter=this.plugin.getCore().getSafeTTeleporter();
        event.setTo(teleporter.getSafeLocation(event.getPlayer(),portalDest));
      }
      event.setPortalTravelAgent(agent);
      event.useTravelAgent(true);
      MVPortalEvent portalEvent=new MVPortalEvent(portalDest,event.getPlayer(),agent);
      this.plugin.getServer().getPluginManager().callEvent(portalEvent);
      if (portalEvent.isCancelled()) {
        event.setCancelled(true);
        this.plugin.log(Level.FINE,"String_Node_Str");
        return;
      }
      this.plugin.log(Level.FINE,"String_Node_Str");
    }
 else     if (!this.plugin.getMainConfig().getBoolean("String_Node_Str",false)) {
      event.getPlayer().sendMessage("String_Node_Str" + ChatColor.RED + "String_Node_Str"+ ChatColor.RED+ "String_Node_Str");
      event.setCancelled(true);
    }
  }
}