Program: 12719
Project: 12719
Buggy source:
@Override public void registerEntitys(){
  BiomeGenBase[] allBiomes=BiomeGenBase.getBiomeGenArray();
  allBiomes=allBiomes.clone();
  allBiomes[9]=null;
  allBiomes[8]=null;
  BiomeGenBase[] allBiomesNoVampire=allBiomes.clone();
  int vId=ModBiomes.biomeVampireForest.biomeID;
  if (vId > 0 && vId < allBiomes.length) {
    allBiomesNoVampire[vId]=null;
  }
  BiomeGenBase[] biomes=Iterators.toArray(Iterators.filter(Iterators.forArray(allBiomes),Predicates.notNull()),BiomeGenBase.class);
  allBiomesNoVampire=Iterators.toArray(Iterators.filter(Iterators.forArray(allBiomesNoVampire),Predicates.notNull()),BiomeGenBase.class);
  registerEntity(EntityVampireHunter.class,REFERENCE.ENTITY.VAMPIRE_HUNTER_NAME,BALANCE.VAMPIRE_HUNTER_SPAWN_PROBE,1,2,EnumCreatureType.creature,allBiomesNoVampire);
  registerEntity(EntityVampire.class,REFERENCE.ENTITY.VAMPIRE_NAME,BALANCE.VAMPIRE_SPAWN_PROBE,1,3,EnumCreatureType.monster,allBiomesNoVampire);
  registerEntity(EntityVampireBaron.class,REFERENCE.ENTITY.VAMPIRE_BARON,true);
  EntityList.stringToClassMapping.put("String_Node_Str",EntityVampireBaron.class);
  registerEntity(EntitySaveableVampireMinion.class,REFERENCE.ENTITY.VAMPIRE_MINION_SAVEABLE_NAME,false);
  registerEntity(EntityRemoteVampireMinion.class,REFERENCE.ENTITY.VAMPIRE_MINION_REMOTE_NAME,false);
  registerEntity(EntityDeadMob.class,REFERENCE.ENTITY.DEAD_MOB_NAME,false);
  registerEntity(EntityDracula.class,REFERENCE.ENTITY.DRACULA_NAME,false);
  registerEntity(EntityGhost.class,REFERENCE.ENTITY.GHOST_NAME,true);
  registerEntity(EntityBlindingBat.class,REFERENCE.ENTITY.BLINDING_BAT_NAME,false);
  registerEntity(EntityDummyBittenAnimal.class,REFERENCE.ENTITY.DUMMY_CREATURE,false);
  registerEntity(EntityPortalGuard.class,REFERENCE.ENTITY.PORTAL_GUARD,true);
  Item item=new ItemSpawnEgg(spawnableEntityNames);
  GameRegistry.registerItem(item,ItemSpawnEgg.name);
  OreDictionary.registerOre("String_Node_Str",item);
}

Fixed version (ground truth):
@Override public void registerEntitys(){
  BiomeGenBase[] allBiomes=BiomeGenBase.getBiomeGenArray();
  allBiomes=Arrays.copyOf(allBiomes,allBiomes.length);
  allBiomes[9]=null;
  allBiomes[8]=null;
  BiomeGenBase[] allBiomesNoVampire=Arrays.copyOf(allBiomes,allBiomes.length);
  int vId=ModBiomes.biomeVampireForest.biomeID;
  if (vId > 0 && vId < allBiomes.length) {
    allBiomesNoVampire[vId]=null;
  }
  BiomeGenBase[] biomes=Iterators.toArray(Iterators.filter(Iterators.forArray(allBiomes),Predicates.notNull()),BiomeGenBase.class);
  allBiomesNoVampire=Iterators.toArray(Iterators.filter(Iterators.forArray(allBiomesNoVampire),Predicates.notNull()),BiomeGenBase.class);
  Logger.t(ArrayUtils.toString(allBiomesNoVampire));
  registerEntity(EntityVampireHunter.class,REFERENCE.ENTITY.VAMPIRE_HUNTER_NAME,BALANCE.VAMPIRE_HUNTER_SPAWN_PROBE,1,2,EnumCreatureType.monster,allBiomesNoVampire);
  registerEntity(EntityVampire.class,REFERENCE.ENTITY.VAMPIRE_NAME,BALANCE.VAMPIRE_SPAWN_PROBE,1,3,EnumCreatureType.monster,allBiomesNoVampire);
  registerEntity(EntityVampireBaron.class,REFERENCE.ENTITY.VAMPIRE_BARON,true);
  EntityList.stringToClassMapping.put("String_Node_Str",EntityVampireBaron.class);
  registerEntity(EntitySaveableVampireMinion.class,REFERENCE.ENTITY.VAMPIRE_MINION_SAVEABLE_NAME,false);
  registerEntity(EntityRemoteVampireMinion.class,REFERENCE.ENTITY.VAMPIRE_MINION_REMOTE_NAME,false);
  registerEntity(EntityDeadMob.class,REFERENCE.ENTITY.DEAD_MOB_NAME,false);
  registerEntity(EntityDracula.class,REFERENCE.ENTITY.DRACULA_NAME,false);
  registerEntity(EntityGhost.class,REFERENCE.ENTITY.GHOST_NAME,true);
  registerEntity(EntityBlindingBat.class,REFERENCE.ENTITY.BLINDING_BAT_NAME,false);
  registerEntity(EntityDummyBittenAnimal.class,REFERENCE.ENTITY.DUMMY_CREATURE,false);
  registerEntity(EntityPortalGuard.class,REFERENCE.ENTITY.PORTAL_GUARD,true);
  Item item=new ItemSpawnEgg(spawnableEntityNames);
  GameRegistry.registerItem(item,ItemSpawnEgg.name);
  OreDictionary.registerOre("String_Node_Str",item);
}