Enhanced error message
Enhanced error message

wkentaro/chainer,niboshi/chainer,okuta/chainer,wkentaro/chainer,hvy/chainer,niboshi/chainer,pfnet/chainer,chainer/chainer,chainer/chainer,hvy/chainer,wkentaro/chainer,okuta/chainer,chainer/chainer,chainer/chainer,hvy/chainer,niboshi/chainer,okuta/chainer,hvy/chainer,okuta/chainer,wkentaro/chainer,niboshi/chainer