[pytorch] Early return in nn.EmbeddingBag when weight is empty (#46572)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46572
When `num_samples == 0`, grid becomes zero. Although CUDA just silently proceeds, `cudaGetLastError()` will complain about the `Error: invalid configuration argument`. So it's actually failing in some future places that becomes really hard to debug.
Reviewed By: jianyuh
Differential Revision: D24409874
fbshipit-source-id: ca54de13b1ab48204bbad265e3f55b56b94a1a2f
