Program: 59904
Project: 59904
Buggy source:
@SubscribeEvent public void onInteract(PlayerInteractEvent event){
  ItemStack held=event.entityPlayer.getCurrentEquippedItem();
  int slot=event.entityPlayer.inventory.currentItem;
  if (held == null || !(held.getItem() instanceof IChiselItem)) {
    return;
  }
  IChiselItem chisel=(IChiselItem)held.getItem();
switch (event.action) {
case LEFT_CLICK_BLOCK:
    int x=event.x, y=event.y, z=event.z;
  Block block=event.world.getBlock(x,y,z);
int metadata=event.world.getBlockMetadata(x,y,z);
List<ICarvingVariation> list=Carving.chisel.getVariations(block,metadata);
if (list == null || list.isEmpty()) {
break;
}
ICarvingVariation[] variations=list.toArray(new CarvingVariation[]{});
if (chisel.canChiselBlock(event.world,x,y,z,block,metadata)) {
ItemStack target=General.getChiselTarget(held);
ChiselMode mode=General.getChiselMode(held);
ForgeDirection sideHit=ForgeDirection.VALID_DIRECTIONS[event.face];
if (target != null) {
for (ICarvingVariation v : variations) {
if (v.getBlock() == Block.getBlockFromItem(target.getItem()) && v.getBlockMeta() == target.getItemDamage()) {
mode.chiselAll(event.entityPlayer,event.world,x,y,z,sideHit,v);
}
}
}
 else {
int idx=0;
for (int i=0; i < variations.length; i++) {
ICarvingVariation v=variations[i];
if (v.getBlock() == block && v.getBlockMeta() == metadata) {
idx=(i + 1) % variations.length;
}
}
ICarvingVariation newVar=variations[idx];
mode.chiselAll(event.entityPlayer,event.world,x,y,z,sideHit,newVar);
event.entityPlayer.inventory.currentItem=slot;
}
}
break;
case RIGHT_CLICK_AIR:
case RIGHT_CLICK_BLOCK:
if (event.world.getTotalWorldTime() == lastTickClick) {
break;
}
 else {
lastTickClick=event.world.getTotalWorldTime();
}
if (!event.world.isRemote && event.entityPlayer.isSneaking()) {
ChiselMode mode=General.getChiselMode(held);
General.setChiselMode(held,ChiselMode.values()[(mode.ordinal() + 1) % 3]);
event.entityPlayer.addChatMessage(new ChatComponentText(General.getChiselMode(held).toString()));
break;
}
if (!event.world.isRemote && chisel.canOpenGui(event.world,event.entityPlayer,held)) {
event.entityPlayer.openGui(Chisel.instance,0,event.world,0,0,0);
}
break;
}
}

Fixed version (ground truth):
@SubscribeEvent public void onInteract(PlayerInteractEvent event){
  ItemStack held=event.entityPlayer.getCurrentEquippedItem();
  int slot=event.entityPlayer.inventory.currentItem;
  if (held == null || !(held.getItem() instanceof IChiselItem)) {
    return;
  }
  IChiselItem chisel=(IChiselItem)held.getItem();
switch (event.action) {
case LEFT_CLICK_BLOCK:
    int x=event.x, y=event.y, z=event.z;
  Block block=event.world.getBlock(x,y,z);
int metadata=event.world.getBlockMetadata(x,y,z);
List<ICarvingVariation> list=Carving.chisel.getVariations(block,metadata);
if (list == null || list.isEmpty()) {
break;
}
ICarvingVariation[] variations=list.toArray(new CarvingVariation[]{});
if (chisel.canChiselBlock(event.world,x,y,z,block,metadata)) {
ItemStack target=General.getChiselTarget(held);
ChiselMode mode=General.getChiselMode(held);
ForgeDirection sideHit=ForgeDirection.VALID_DIRECTIONS[event.face];
if (target != null) {
for (ICarvingVariation v : variations) {
if (v.getBlock() == Block.getBlockFromItem(target.getItem()) && v.getBlockMeta() == target.getItemDamage()) {
mode.chiselAll(event.entityPlayer,event.world,x,y,z,sideHit,v);
}
}
}
 else {
int idx=0;
for (int i=0; i < variations.length; i++) {
ICarvingVariation v=variations[i];
if (v.getBlock() == block && v.getBlockMeta() == metadata) {
idx=(i + 1) % variations.length;
}
}
ICarvingVariation newVar=variations[idx];
mode.chiselAll(event.entityPlayer,event.world,x,y,z,sideHit,newVar);
event.entityPlayer.inventory.currentItem=slot;
}
}
break;
case RIGHT_CLICK_AIR:
case RIGHT_CLICK_BLOCK:
if (event.world.getTotalWorldTime() == lastTickClick) {
break;
}
 else {
lastTickClick=event.world.getTotalWorldTime();
}
if (!event.world.isRemote && chisel.canOpenGui(event.world,event.entityPlayer,held)) {
event.entityPlayer.openGui(Chisel.instance,0,event.world,0,0,0);
}
break;
}
}