A boolean array of the axis's length, or of the dataset's whole shape, is
a mask h5py would apply (NotImplementedError here); one of any other shape
(np.array(True), a wrong length) is a key h5py itself refuses with
TypeError, which test_errors_match_h5py requires us to match.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>