Program: 34018
Project: 34018
Buggy source:
/** 
 * Checks if a location is within the home boundaries of a player. If coop is true, this check includes coop players.
 * @param player
 * @param coop
 * @param loc
 * @return true if the location is within home boundaries
 */
public boolean locationIsAtHome(final Player player,boolean coop,Location loc){
  Set<Location> islandTestLocations=new HashSet<Location>();
  if (plugin.getPlayers().hasIsland(player.getUniqueId())) {
    islandTestLocations.add(plugin.getPlayers().getIslandLocation(player.getUniqueId()));
    if (Settings.createNether && Settings.newNether) {
      islandTestLocations.add(netherIsland(plugin.getPlayers().getIslandLocation(player.getUniqueId())));
    }
  }
 else   if (plugin.getPlayers().inTeam(player.getUniqueId())) {
    islandTestLocations.add(plugin.getPlayers().getTeamIslandLocation(player.getUniqueId()));
    if (Settings.createNether && Settings.newNether) {
      islandTestLocations.add(netherIsland(plugin.getPlayers().getTeamIslandLocation(player.getUniqueId())));
    }
  }
  if (coop) {
    islandTestLocations.addAll(CoopPlay.getInstance().getCoopIslands(player));
  }
  if (islandTestLocations.isEmpty()) {
    return false;
  }
  for (  Location islandTestLocation : islandTestLocations) {
    if (islandTestLocation != null && islandTestLocation.getWorld() != null && islandTestLocation.getWorld().equals(loc.getWorld())) {
      int protectionRange=Settings.island_protectionRange;
      if (getIslandAt(islandTestLocation) != null) {
        Island island=getProtectedIslandAt(islandTestLocation);
        if (island != null) {
          protectionRange=island.getProtectionSize();
        }
      }
      if (loc.getX() > islandTestLocation.getX() - protectionRange / 2 && loc.getX() < islandTestLocation.getX() + protectionRange / 2 && loc.getZ() > islandTestLocation.getZ() - protectionRange / 2 && loc.getZ() < islandTestLocation.getZ() + protectionRange / 2) {
        return true;
      }
    }
  }
  return false;
}

Fixed version (ground truth):
/** 
 * Checks if a location is within the home boundaries of a player. If coop is true, this check includes coop players.
 * @param player
 * @param coop
 * @param loc
 * @return true if the location is within home boundaries
 */
public boolean locationIsAtHome(final Player player,boolean coop,Location loc){
  Set<Location> islandTestLocations=new HashSet<Location>();
  if (plugin.getPlayers().hasIsland(player.getUniqueId())) {
    islandTestLocations.add(plugin.getPlayers().getIslandLocation(player.getUniqueId()));
    if (Settings.createNether && Settings.newNether && ASkyBlock.getNetherWorld() != null) {
      islandTestLocations.add(netherIsland(plugin.getPlayers().getIslandLocation(player.getUniqueId())));
    }
  }
 else   if (plugin.getPlayers().inTeam(player.getUniqueId())) {
    islandTestLocations.add(plugin.getPlayers().getTeamIslandLocation(player.getUniqueId()));
    if (Settings.createNether && Settings.newNether && ASkyBlock.getNetherWorld() != null) {
      islandTestLocations.add(netherIsland(plugin.getPlayers().getTeamIslandLocation(player.getUniqueId())));
    }
  }
  if (coop) {
    islandTestLocations.addAll(CoopPlay.getInstance().getCoopIslands(player));
  }
  if (islandTestLocations.isEmpty()) {
    return false;
  }
  for (  Location islandTestLocation : islandTestLocations) {
    if (islandTestLocation != null && islandTestLocation.getWorld() != null && islandTestLocation.getWorld().equals(loc.getWorld())) {
      int protectionRange=Settings.island_protectionRange;
      if (getIslandAt(islandTestLocation) != null) {
        Island island=getProtectedIslandAt(islandTestLocation);
        if (island != null) {
          protectionRange=island.getProtectionSize();
        }
      }
      if (loc.getX() > islandTestLocation.getX() - protectionRange / 2 && loc.getX() < islandTestLocation.getX() + protectionRange / 2 && loc.getZ() > islandTestLocation.getZ() - protectionRange / 2 && loc.getZ() < islandTestLocation.getZ() + protectionRange / 2) {
        return true;
      }
    }
  }
  return false;
}