Bug: NumpyReader for .npz files with variable names.

[mandelkow]

MONAI/monai/data/image_reader.py

Line 1071 in 6e5fdc0

npz_keys = [f"arr_{i}" for i in range(len(img))] if self.npz_keys is None else self.npz_keys

If npz_keys is not given, NumpyReader assumes variables in .npz files to be named arr_0, arr_1,...
This may or may not be true. It would be better to use the variable names from the file like so:

                npz_keys = self.npz_keys if self.npz_keys else list( img.keys() ) # or img.files