`LeRobotDataset.save_episode()` raised
`ValueError: cannot reshape array of size 0 into shape (0)` whenever a
declared non-string feature had a zero-width dimension (e.g. `shape=(0,)`).
The root cause was `compute_episode_stats` running stats on every
non-string/language feature, then `RunningQuantileStats.update` calling
`batch.reshape(-1, batch.shape[-1])` on the empty array.
Skip features whose declared `shape` contains a zero dim, mirroring the
existing skip for `string` / `language` dtype features.
Fixes#3654
Mahbod
f59260f4aa