Use appropriate error type
Use appropriate error type

jnishi/chainer,niboshi/chainer,niboshi/chainer,ktnyt/chainer,wkentaro/chainer,ktnyt/chainer,hvy/chainer,keisuke-umezawa/chainer,jnishi/chainer,keisuke-umezawa/chainer,ktnyt/chainer,ktnyt/chainer,keisuke-umezawa/chainer,chainer/chainer,wkentaro/chainer,okuta/chainer,wkentaro/chainer,hvy/chainer,pfnet/chainer,chainer/chainer,hvy/chainer,wkentaro/chainer,chainer/chainer,jnishi/chainer,okuta/chainer,niboshi/chainer,okuta/chainer,niboshi/chainer,okuta/chainer,chainer/chainer,tkerola/chainer,hvy/chainer,keisuke-umezawa/chainer,jnishi/chainer