Program: 58028
Project: 58028
Buggy source:
@Override public boolean execute(final PlotPlayer plr,final String... args){
  String schematic="String_Node_Str";
  if (args.length >= 1) {
    schematic=args[0];
  }
  final Location loc=plr.getLocation();
  final Plot plot=MainUtil.getPlot(loc);
  if (plot == null) {
    return sendMessage(plr,C.NOT_IN_PLOT);
  }
  final int currentPlots=Settings.GLOBAL_LIMIT ? MainUtil.getPlayerPlotCount(plr) : MainUtil.getPlayerPlotCount(loc.getWorld(),plr);
  if (currentPlots >= MainUtil.getAllowedPlots(plr)) {
    return sendMessage(plr,C.CANT_CLAIM_MORE_PLOTS);
  }
  if (!MainUtil.canClaim(plr,plot)) {
    return sendMessage(plr,C.PLOT_IS_CLAIMED);
  }
  final PlotWorld world=PlotSquared.getPlotWorld(plot.world);
  if ((PlotSquared.economy != null) && world.USE_ECONOMY) {
    final double cost=world.PLOT_PRICE;
    if (cost > 0d) {
      if (EconHandler.getBalance(plr) < cost) {
        return sendMessage(plr,C.CANNOT_AFFORD_PLOT,"String_Node_Str" + cost);
      }
      EconHandler.withdrawPlayer(plr,cost);
      sendMessage(plr,C.REMOVED_BALANCE,cost + "String_Node_Str");
    }
  }
  if (!schematic.equals("String_Node_Str")) {
    if (world.SCHEMATIC_CLAIM_SPECIFY) {
      if (!world.SCHEMATICS.contains(schematic.toLowerCase())) {
        return sendMessage(plr,C.SCHEMATIC_INVALID,"String_Node_Str" + schematic);
      }
      if (!Permissions.hasPermission(plr,"String_Node_Str" + schematic) && !plr.hasPermission("String_Node_Str")) {
        return sendMessage(plr,C.NO_SCHEMATIC_PERMISSION,schematic);
      }
    }
  }
  return claimPlot(plr,plot,false,schematic,false) || sendMessage(plr,C.PLOT_NOT_CLAIMED);
}

Fixed version (ground truth):
@Override public boolean execute(final PlotPlayer plr,final String... args){
  String schematic="String_Node_Str";
  if (args.length >= 1) {
    schematic=args[0];
  }
  final Location loc=plr.getLocation();
  final Plot plot=MainUtil.getPlot(loc);
  if (plot == null) {
    return sendMessage(plr,C.NOT_IN_PLOT);
  }
  final int currentPlots=Settings.GLOBAL_LIMIT ? MainUtil.getPlayerPlotCount(plr) : MainUtil.getPlayerPlotCount(loc.getWorld(),plr);
  if (currentPlots >= MainUtil.getAllowedPlots(plr)) {
    return sendMessage(plr,C.CANT_CLAIM_MORE_PLOTS);
  }
  if (!MainUtil.canClaim(plr,plot)) {
    return sendMessage(plr,C.PLOT_IS_CLAIMED);
  }
  final PlotWorld world=PlotSquared.getPlotWorld(plot.world);
  if ((EconHandler.manager != null) && world.USE_ECONOMY) {
    final double cost=world.PLOT_PRICE;
    if (cost > 0d) {
      if (EconHandler.manager.getMoney(plr) < cost) {
        return sendMessage(plr,C.CANNOT_AFFORD_PLOT,"String_Node_Str" + cost);
      }
      EconHandler.manager.withdrawMoney(plr,cost);
      sendMessage(plr,C.REMOVED_BALANCE,cost + "String_Node_Str");
    }
  }
  if (!schematic.equals("String_Node_Str")) {
    if (world.SCHEMATIC_CLAIM_SPECIFY) {
      if (!world.SCHEMATICS.contains(schematic.toLowerCase())) {
        return sendMessage(plr,C.SCHEMATIC_INVALID,"String_Node_Str" + schematic);
      }
      if (!Permissions.hasPermission(plr,"String_Node_Str" + schematic) && !plr.hasPermission("String_Node_Str")) {
        return sendMessage(plr,C.NO_SCHEMATIC_PERMISSION,schematic);
      }
    }
  }
  return claimPlot(plr,plot,false,schematic,false) || sendMessage(plr,C.PLOT_NOT_CLAIMED);
}