Program: 33881
Project: 33881
Buggy source:
@EventHandler(priority=EventPriority.LOWEST,ignoreCancelled=true) public void onPlayerMove(PlayerMoveEvent e){
  if (Settings.rainDamage == 0 && Settings.acidDamage == 0) {
    return;
  }
  final Player player=e.getPlayer();
  if (player.isDead() || player.getGameMode().toString().startsWith("String_Node_Str")) {
    return;
  }
  if (!player.getWorld().equals(ASkyBlock.getIslandWorld())) {
    return;
  }
  if (player.isOp()) {
    if (!Settings.damageOps) {
      return;
    }
  }
 else   if (VaultHelper.checkPerm(player,Settings.PERMPREFIX + "String_Node_Str") || VaultHelper.checkPerm(player,Settings.PERMPREFIX + "String_Node_Str")) {
    return;
  }
  if (player.getGameMode().equals(GameMode.CREATIVE)) {
    return;
  }
  if (DEBUG)   plugin.getLogger().info("String_Node_Str" + e.getEventName());
  final Location playerLoc=player.getLocation();
  final Block block=playerLoc.getBlock();
  final Block head=block.getRelative(BlockFace.UP);
  if (Settings.rainDamage > 0D && isRaining) {
    Biome biome=playerLoc.getBlock().getBiome();
    if (biome != Biome.DESERT && biome != Biome.DESERT_HILLS && biome != Biome.SAVANNA && biome != Biome.MESA && biome != Biome.HELL) {
      if (isSafeFromRain(player)) {
        wetPlayers.remove(player);
      }
 else {
        if (!wetPlayers.contains(player)) {
          wetPlayers.add(player);
          new BukkitRunnable(){
            @Override public void run(){
              if (!isRaining || player.isDead() || isSafeFromRain(player)|| Settings.rainDamage <= 0D) {
                wetPlayers.remove(player);
                this.cancel();
              }
 else {
                double health=player.getHealth() - (Settings.rainDamage - Settings.rainDamage * getDamageReduced(player));
                if (health < 0D) {
                  health=0D;
                }
 else                 if (health > player.getMaxHealth()) {
                  health=player.getMaxHealth();
                }
                player.setHealth(health);
                if (plugin.getServer().getVersion().contains("String_Node_Str") || plugin.getServer().getVersion().contains("String_Node_Str")) {
                  player.getWorld().playSound(playerLoc,Sound.valueOf("String_Node_Str"),3F,3F);
                }
 else {
                  player.getWorld().playSound(playerLoc,Sound.ENTITY_CREEPER_PRIMED,3F,3F);
                }
              }
            }
          }
.runTaskTimer(plugin,0L,20L);
        }
      }
    }
  }
  if (playerLoc.getBlockY() < 1 && Settings.GAMETYPE.equals(GameType.ACIDISLAND)) {
    final Vector v=new Vector(player.getVelocity().getX(),1D,player.getVelocity().getZ());
    player.setVelocity(v);
  }
  if (burningPlayers.contains(player)) {
    if (DEBUG)     plugin.getLogger().info("String_Node_Str");
    return;
  }
  if (isSafeFromAcid(player)) {
    if (DEBUG)     plugin.getLogger().info("String_Node_Str");
    return;
  }
  burningPlayers.add(player);
  new BukkitRunnable(){
    @Override public void run(){
      if (player.isDead() || isSafeFromAcid(player)) {
        burningPlayers.remove(player);
        this.cancel();
      }
 else {
        if (!Settings.acidDamageType.isEmpty()) {
          for (          PotionEffectType t : Settings.acidDamageType) {
            if (t.equals(PotionEffectType.BLINDNESS) || t.equals(PotionEffectType.CONFUSION) || t.equals(PotionEffectType.HUNGER)|| t.equals(PotionEffectType.SLOW)|| t.equals(PotionEffectType.SLOW_DIGGING)|| t.equals(PotionEffectType.WEAKNESS)) {
              player.addPotionEffect(new PotionEffect(t,600,1));
            }
 else {
              player.addPotionEffect(new PotionEffect(t,200,1));
            }
          }
        }
        if (Settings.acidDamage > 0D) {
          double health=player.getHealth() - (Settings.acidDamage - Settings.acidDamage * getDamageReduced(player));
          if (health < 0D) {
            health=0D;
          }
 else           if (health > player.getMaxHealth()) {
            health=player.getMaxHealth();
          }
          player.setHealth(health);
          if (plugin.getServer().getVersion().contains("String_Node_Str") || plugin.getServer().getVersion().contains("String_Node_Str")) {
            player.getWorld().playSound(playerLoc,Sound.valueOf("String_Node_Str"),3F,3F);
          }
 else {
            player.getWorld().playSound(playerLoc,Sound.ENTITY_CREEPER_PRIMED,3F,3F);
          }
        }
      }
    }
  }
.runTaskTimer(plugin,0L,20L);
}

Fixed version (ground truth):
@EventHandler(priority=EventPriority.LOWEST,ignoreCancelled=true) public void onPlayerMove(PlayerMoveEvent e){
  if (Settings.rainDamage == 0 && Settings.acidDamage == 0) {
    return;
  }
  final Player player=e.getPlayer();
  if (player.isDead() || player.getGameMode().toString().startsWith("String_Node_Str")) {
    return;
  }
  if (plugin.getPlayers().isInTeleport(player.getUniqueId())) {
    return;
  }
  if (!player.getWorld().equals(ASkyBlock.getIslandWorld())) {
    return;
  }
  if (player.isOp()) {
    if (!Settings.damageOps) {
      return;
    }
  }
 else   if (VaultHelper.checkPerm(player,Settings.PERMPREFIX + "String_Node_Str") || VaultHelper.checkPerm(player,Settings.PERMPREFIX + "String_Node_Str")) {
    return;
  }
  if (player.getGameMode().equals(GameMode.CREATIVE)) {
    return;
  }
  if (DEBUG)   plugin.getLogger().info("String_Node_Str" + e.getEventName());
  final Location playerLoc=player.getLocation();
  final Block block=playerLoc.getBlock();
  final Block head=block.getRelative(BlockFace.UP);
  if (Settings.rainDamage > 0D && isRaining) {
    Biome biome=playerLoc.getBlock().getBiome();
    if (biome != Biome.DESERT && biome != Biome.DESERT_HILLS && biome != Biome.SAVANNA && biome != Biome.MESA && biome != Biome.HELL) {
      if (isSafeFromRain(player)) {
        wetPlayers.remove(player);
      }
 else {
        if (!wetPlayers.contains(player)) {
          wetPlayers.add(player);
          new BukkitRunnable(){
            @Override public void run(){
              if (!isRaining || player.isDead() || isSafeFromRain(player)|| Settings.rainDamage <= 0D) {
                wetPlayers.remove(player);
                this.cancel();
              }
 else {
                double health=player.getHealth() - (Settings.rainDamage - Settings.rainDamage * getDamageReduced(player));
                if (health < 0D) {
                  health=0D;
                }
 else                 if (health > player.getMaxHealth()) {
                  health=player.getMaxHealth();
                }
                player.setHealth(health);
                if (plugin.getServer().getVersion().contains("String_Node_Str") || plugin.getServer().getVersion().contains("String_Node_Str")) {
                  player.getWorld().playSound(playerLoc,Sound.valueOf("String_Node_Str"),3F,3F);
                }
 else {
                  player.getWorld().playSound(playerLoc,Sound.ENTITY_CREEPER_PRIMED,3F,3F);
                }
              }
            }
          }
.runTaskTimer(plugin,0L,20L);
        }
      }
    }
  }
  if (playerLoc.getBlockY() < 1 && Settings.GAMETYPE.equals(GameType.ACIDISLAND)) {
    final Vector v=new Vector(player.getVelocity().getX(),1D,player.getVelocity().getZ());
    player.setVelocity(v);
  }
  if (burningPlayers.contains(player)) {
    if (DEBUG)     plugin.getLogger().info("String_Node_Str");
    return;
  }
  if (isSafeFromAcid(player)) {
    if (DEBUG)     plugin.getLogger().info("String_Node_Str");
    return;
  }
  burningPlayers.add(player);
  new BukkitRunnable(){
    @Override public void run(){
      if (player.isDead() || isSafeFromAcid(player)) {
        burningPlayers.remove(player);
        this.cancel();
      }
 else {
        if (!Settings.acidDamageType.isEmpty()) {
          for (          PotionEffectType t : Settings.acidDamageType) {
            if (t.equals(PotionEffectType.BLINDNESS) || t.equals(PotionEffectType.CONFUSION) || t.equals(PotionEffectType.HUNGER)|| t.equals(PotionEffectType.SLOW)|| t.equals(PotionEffectType.SLOW_DIGGING)|| t.equals(PotionEffectType.WEAKNESS)) {
              player.addPotionEffect(new PotionEffect(t,600,1));
            }
 else {
              player.addPotionEffect(new PotionEffect(t,200,1));
            }
          }
        }
        if (Settings.acidDamage > 0D) {
          double health=player.getHealth() - (Settings.acidDamage - Settings.acidDamage * getDamageReduced(player));
          if (health < 0D) {
            health=0D;
          }
 else           if (health > player.getMaxHealth()) {
            health=player.getMaxHealth();
          }
          player.setHealth(health);
          if (plugin.getServer().getVersion().contains("String_Node_Str") || plugin.getServer().getVersion().contains("String_Node_Str")) {
            player.getWorld().playSound(playerLoc,Sound.valueOf("String_Node_Str"),3F,3F);
          }
 else {
            player.getWorld().playSound(playerLoc,Sound.ENTITY_CREEPER_PRIMED,3F,3F);
          }
        }
      }
    }
  }
.runTaskTimer(plugin,0L,20L);
}