See zarr-developers/zarr-python#2508 for context.

Since numcodecs supports registering custom codecs in downstream libraries, there can be situations where the environment in which data was encoded is not the same as the environment in which the data is decoded (e.g. opening a Zarr archive that was created in a different environment). This can lead to missing codecs.

It would be a nice UX improvement if you catch that error and can offer codec specific solutions.

This change would enable something like:

import numcodecs

try: 
    numcodecs.get_codec({"codec_id": "imagecodecs_jpeg2k"})
except UnknownCodecError as error:
    if error.codec_id == "imagecodecs_jpeg2k":
        raise RuntimeError("This Zarr archive requires `imagecodecs`, to install it use ...") from error

TODO:

• Unit tests and/or doctests in docstrings
• Tests pass locally
• Docstrings and API docs for any new/modified user-facing classes and functions
• Changes documented in docs/release.rst
• Docs build locally
• GitHub Actions CI passes
• Test coverage to 100% (Codecov passes)