Program: 58151
Project: 58151
Buggy source:
public static void setMask(Player p,Location l){
  try {
    LocalSession s;
    if (PlotMain.worldEdit == null) {
      s=WorldEdit.getInstance().getSession(p.getName());
    }
 else {
      s=PlotMain.worldEdit.getSession(p);
    }
    PlotId id=PlayerFunctions.getPlot(l);
    if (id != null) {
      Plot plot=PlotMain.getPlots(l.getWorld()).get(id);
      if (plot != null) {
        boolean r;
        r=(plot.getOwner() != null) && plot.getOwner().equals(p.getUniqueId());
        if (!r) {
          if ((plot.helpers.contains(DBFunc.everyone) || plot.helpers.contains(p.getUniqueId()))) {
            r=true;
          }
 else           if (p.hasPermission("String_Node_Str")) {
            removeMask(p,s);
            return;
          }
        }
 else {
          World w=p.getWorld();
          Location bloc=PlotHelper.getPlotBottomLoc(w,plot.id);
          Location tloc=PlotHelper.getPlotTopLoc(w,plot.id);
          Vector bvec=new Vector(bloc.getBlockX() + 1,bloc.getBlockY() + 1,bloc.getBlockZ() + 1);
          Vector tvec=new Vector(tloc.getBlockX(),tloc.getBlockY(),tloc.getBlockZ());
          LocalWorld lw=PlotMain.worldEdit.wrapPlayer(p).getWorld();
          CuboidRegion region=new CuboidRegion(lw,bvec,tvec);
          com.sk89q.worldedit.masks.RegionMask mask=new com.sk89q.worldedit.masks.RegionMask(region);
          s.setMask(mask);
          return;
        }
      }
    }
    if (noMask(s)) {
      BukkitPlayer plr=PlotMain.worldEdit.wrapPlayer(p);
      Vector p1=new Vector(69,69,69), p2=new Vector(69,69,69);
      s.setMask(new com.sk89q.worldedit.masks.RegionMask(new CuboidRegion(plr.getWorld(),p1,p2)));
    }
  }
 catch (  Exception e) {
  }
}

Fixed version (ground truth):
public static void setMask(Player p,Location l){
  try {
    LocalSession s;
    if (PlotMain.worldEdit == null) {
      s=WorldEdit.getInstance().getSession(p.getName());
    }
 else {
      s=PlotMain.worldEdit.getSession(p);
    }
    PlotId id=PlayerFunctions.getPlot(l);
    if (id != null) {
      Plot plot=PlotMain.getPlots(l.getWorld()).get(id);
      if (plot != null) {
        boolean r;
        r=(plot.getOwner() != null) && plot.getOwner().equals(p.getUniqueId()) || plot.helpers.contains(DBFunc.everyone) || plot.helpers.contains(p.getUniqueId());
        if (!r) {
          if (p.hasPermission("String_Node_Str")) {
            removeMask(p,s);
            return;
          }
        }
 else {
          World w=p.getWorld();
          Location bloc=PlotHelper.getPlotBottomLoc(w,plot.id);
          Location tloc=PlotHelper.getPlotTopLoc(w,plot.id);
          Vector bvec=new Vector(bloc.getBlockX() + 1,bloc.getBlockY() + 1,bloc.getBlockZ() + 1);
          Vector tvec=new Vector(tloc.getBlockX(),tloc.getBlockY(),tloc.getBlockZ());
          LocalWorld lw=PlotMain.worldEdit.wrapPlayer(p).getWorld();
          CuboidRegion region=new CuboidRegion(lw,bvec,tvec);
          com.sk89q.worldedit.masks.RegionMask mask=new com.sk89q.worldedit.masks.RegionMask(region);
          s.setMask(mask);
          return;
        }
      }
    }
    if (noMask(s)) {
      BukkitPlayer plr=PlotMain.worldEdit.wrapPlayer(p);
      Vector p1=new Vector(69,69,69), p2=new Vector(69,69,69);
      s.setMask(new com.sk89q.worldedit.masks.RegionMask(new CuboidRegion(plr.getWorld(),p1,p2)));
    }
  }
 catch (  Exception e) {
  }
}