Program: 174579
Project: 174579
Buggy source:
public EntityAquamarine(World worldIn){
  super(worldIn);
  this.moveHelper=new EntityFlyHelper(this);
  this.setSize(0.4F,0.8F);
  this.seePastDoors();
  this.setValidCut(GemCuts.TINY);
  this.setValidCut(GemCuts.TEARDROP);
  this.setValidPlacement(GemPlacements.BACK_OF_HEAD);
  this.setValidPlacement(GemPlacements.FOREHEAD);
  this.setValidPlacement(GemPlacements.LEFT_EYE);
  this.setValidPlacement(GemPlacements.RIGHT_EYE);
  this.setValidPlacement(GemPlacements.LEFT_CHEEK);
  this.setValidPlacement(GemPlacements.RIGHT_CHEEK);
  this.setValidPlacement(GemPlacements.BACK);
  this.setValidPlacement(GemPlacements.CHEST);
  this.setValidPlacement(GemPlacements.BELLY);
  this.stayAI=new EntityAIStay(this);
  this.tasks.addTask(1,new EntityAIFollowDiamond(this,1.0D));
  this.tasks.addTask(2,new EntityAIScan(this));
  this.tasks.addTask(3,new EntityAIOpenDoor(this,true));
  this.tasks.addTask(3,new EntityAIAttackMelee(this,1.0D,true));
  this.tasks.addTask(3,new EntityAIMoveTowardsTarget(this,0.414D,32.0F));
  this.tasks.addTask(4,new EntityAIWatchClosest(this,EntityPlayer.class,16.0F));
  this.tasks.addTask(4,new EntityAIWatchClosest(this,EntityMob.class,16.0F));
  this.tasks.addTask(5,new EntityAIStandGuard(this,0.6D));
  this.tasks.addTask(6,new EntityAILookIdle(this));
  this.getEntityAttribute(SharedMonsterAttributes.MAX_HEALTH).setBaseValue(40.0D);
  this.getEntityAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).setBaseValue(2.0D);
  this.getEntityAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).setBaseValue(1.0D);
  this.droppedGemItem=ModItems.AQUAMARINE_GEM;
  this.droppedCrackedGemItem=ModItems.CRACKED_AQUAMARINE_GEM;
}

Fixed version (ground truth):
public EntityAquamarine(World worldIn){
  super(worldIn);
  this.moveHelper=new EntityFlyHelper(this);
  this.setSize(0.4F,0.8F);
  this.seePastDoors();
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.BACK_OF_HEAD);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.FOREHEAD);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.LEFT_EYE);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.RIGHT_EYE);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.LEFT_CHEEK);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.RIGHT_CHEEK);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.BACK);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.CHEST);
  this.setCutPlacement(GemCuts.TEARDROP,GemPlacements.BELLY);
  this.stayAI=new EntityAIStay(this);
  this.tasks.addTask(1,new EntityAIFollowDiamond(this,1.0D));
  this.tasks.addTask(2,new EntityAIScan(this));
  this.tasks.addTask(3,new EntityAIOpenDoor(this,true));
  this.tasks.addTask(3,new EntityAIAttackMelee(this,1.0D,true));
  this.tasks.addTask(3,new EntityAIMoveTowardsTarget(this,0.414D,32.0F));
  this.tasks.addTask(4,new EntityAIWatchClosest(this,EntityPlayer.class,16.0F));
  this.tasks.addTask(4,new EntityAIWatchClosest(this,EntityMob.class,16.0F));
  this.tasks.addTask(5,new EntityAIStandGuard(this,0.6D));
  this.tasks.addTask(6,new EntityAILookIdle(this));
  this.getEntityAttribute(SharedMonsterAttributes.MAX_HEALTH).setBaseValue(40.0D);
  this.getEntityAttribute(SharedMonsterAttributes.ATTACK_DAMAGE).setBaseValue(2.0D);
  this.getEntityAttribute(SharedMonsterAttributes.MOVEMENT_SPEED).setBaseValue(1.0D);
  this.droppedGemItem=ModItems.AQUAMARINE_GEM;
  this.droppedCrackedGemItem=ModItems.CRACKED_AQUAMARINE_GEM;
}