Program: 3018
Project: 3018
Buggy source:
@Override public void onBlockBreak(BlockBreakEvent event){
  if (event.isCancelled()) {
    return;
  }
  Block target=event.getBlock();
  ItemStack tool=event.getPlayer().getItemInHand();
  Integer maxDamage=0;
  boolean successfulConversion=false;
  for (  OtherBlocksContainer obc : parent.transformList) {
    if (!obc.tool.contains(null) && !obc.tool.contains(tool.getType())) {
      continue;
    }
    if (obc.original != event.getBlock().getType()) {
      continue;
    }
    if (parent.rng.nextDouble() > (obc.chance.doubleValue() / 100)) {
      continue;
    }
    Location location=new Location(target.getWorld(),target.getX(),target.getY(),target.getZ());
    successfulConversion=true;
    try {
      if (obc.droptype.equalsIgnoreCase("String_Node_Str")) {
        target.getWorld().dropItemNaturally(location,new ItemStack(Material.valueOf(obc.dropped),obc.quantity,obc.color));
      }
 else       if (obc.droptype.equalsIgnoreCase("String_Node_Str")) {
        target.getWorld().spawnCreature(new Location(target.getWorld(),location.getX() + 0.5,location.getY() + 1,location.getZ() + 0.5),CreatureType.valueOf(obc.dropped));
      }
 else {
        throw new Exception("String_Node_Str");
      }
    }
 catch (    Exception e) {
      e.printStackTrace();
    }
    maxDamage=(maxDamage < obc.damage) ? obc.damage : maxDamage;
  }
  if (successfulConversion) {
    event.setCancelled(true);
    target.setType(Material.AIR);
    if (parent.getFixedMaxDurability(tool.getType()) < 0 || tool.getType().isBlock()) {
      return;
    }
    tool.setDurability((short)(tool.getDurability() + maxDamage));
    if (tool.getDurability() >= parent.getFixedMaxDurability(tool.getType())) {
      event.getPlayer().setItemInHand(null);
    }
  }
}

Fixed version (ground truth):
@Override public void onBlockBreak(BlockBreakEvent event){
  if (event.isCancelled()) {
    return;
  }
  Block target=event.getBlock();
  ItemStack tool=event.getPlayer().getItemInHand();
  Integer maxDamage=0;
  boolean successfulConversion=false;
  for (  OtherBlocksContainer obc : parent.transformList) {
    if (!obc.tool.contains(null) && !obc.tool.contains(tool.getType())) {
      continue;
    }
    if (obc.original != event.getBlock().getType()) {
      continue;
    }
    if (parent.rng.nextDouble() > (obc.chance.doubleValue() / 100)) {
      continue;
    }
    Location location=new Location(target.getWorld(),target.getX(),target.getY(),target.getZ());
    successfulConversion=true;
    try {
      if (obc.droptype.equalsIgnoreCase("String_Node_Str")) {
        if (Material.valueOf(obc.dropped) != Material.AIR) {
          target.getWorld().dropItemNaturally(location,new ItemStack(Material.valueOf(obc.dropped),obc.quantity,obc.color));
        }
      }
 else       if (obc.droptype.equalsIgnoreCase("String_Node_Str")) {
        target.getWorld().spawnCreature(new Location(target.getWorld(),location.getX() + 0.5,location.getY() + 1,location.getZ() + 0.5),CreatureType.valueOf(obc.dropped));
      }
 else {
        throw new Exception("String_Node_Str");
      }
    }
 catch (    Exception e) {
      e.printStackTrace();
    }
    maxDamage=(maxDamage < obc.damage) ? obc.damage : maxDamage;
  }
  if (successfulConversion) {
    event.setCancelled(true);
    target.setType(Material.AIR);
    if (parent.getFixedMaxDurability(tool.getType()) < 0 || tool.getType().isBlock()) {
      return;
    }
    tool.setDurability((short)(tool.getDurability() + maxDamage));
    if (tool.getDurability() >= parent.getFixedMaxDurability(tool.getType())) {
      event.getPlayer().setItemInHand(null);
    }
  }
}