Program: 156881
Project: 156881
Buggy source:
private BuildingSlot internalGetNextBlock(World world,TileAbstractBuilder builder,LinkedList<BuildingSlotBlock> list){
  iterator.startIteration();
  while (iterator.hasNext()) {
    BuildingSlotBlock slot=iterator.next();
    if (slot.buildStage > buildList.getFirst().buildStage) {
      iterator.reset();
      return null;
    }
    try {
      if (!slot.isAlreadyBuilt(context)) {
        if (slot.mode == Mode.ClearIfInvalid) {
          if (BuildCraftAPI.isSoftBlock(world,slot.x,slot.y,slot.z) || BlockUtil.isUnbreakableBlock(world,slot.x,slot.y,slot.z)) {
            iterator.remove();
          }
 else {
            if (setupForDestroy(builder,context,slot)) {
              iterator.remove();
              clearedLocations.add(new BlockIndex(slot.x,slot.y,slot.z));
              return slot;
            }
          }
        }
 else         if (!slot.schematic.doNotBuild()) {
          if (checkRequirements(builder,slot.schematic)) {
            useRequirements(builder,slot);
            iterator.remove();
            postProcessing.add(slot);
            builtLocations.add(new BlockIndex(slot.x,slot.y,slot.z));
            return slot;
          }
        }
 else {
          postProcessing.add(slot);
          iterator.remove();
        }
      }
 else {
        if (slot.mode == Mode.Build) {
          postProcessing.add(slot);
        }
        iterator.remove();
      }
    }
 catch (    Throwable t) {
      t.printStackTrace();
      BCLog.logger.throwing("String_Node_Str","String_Node_Str",t);
      iterator.remove();
    }
  }
  return null;
}

Fixed version (ground truth):
private BuildingSlot internalGetNextBlock(World world,TileAbstractBuilder builder,LinkedList<BuildingSlotBlock> list){
  if (builder.energyAvailable() < SchematicRegistry.BREAK_ENERGY) {
    iterator.reset();
    return null;
  }
  iterator.startIteration();
  while (iterator.hasNext()) {
    BuildingSlotBlock slot=iterator.next();
    if (slot.buildStage > buildList.getFirst().buildStage) {
      iterator.reset();
      return null;
    }
    try {
      if (!slot.isAlreadyBuilt(context)) {
        if (slot.mode == Mode.ClearIfInvalid) {
          if (BuildCraftAPI.isSoftBlock(world,slot.x,slot.y,slot.z) || BlockUtil.isUnbreakableBlock(world,slot.x,slot.y,slot.z)) {
            iterator.remove();
          }
 else {
            if (setupForDestroy(builder,context,slot)) {
              iterator.remove();
              clearedLocations.add(new BlockIndex(slot.x,slot.y,slot.z));
              return slot;
            }
          }
        }
 else         if (!slot.schematic.doNotBuild()) {
          if (checkRequirements(builder,slot.schematic)) {
            useRequirements(builder,slot);
            iterator.remove();
            postProcessing.add(slot);
            builtLocations.add(new BlockIndex(slot.x,slot.y,slot.z));
            return slot;
          }
        }
 else {
          postProcessing.add(slot);
          iterator.remove();
        }
      }
 else {
        if (slot.mode == Mode.Build) {
          postProcessing.add(slot);
        }
        iterator.remove();
      }
    }
 catch (    Throwable t) {
      t.printStackTrace();
      BCLog.logger.throwing("String_Node_Str","String_Node_Str",t);
      iterator.remove();
    }
  }
  return null;
}