Reference Filesystem: "ValueError: Compression type zstd not supported"

When opening a zstd compressed reference file using:

fs = fsspec.filesystem("reference", fo='s3://esip-qhub-public/ecmwf/ERA5_2020_2022_multivar.json.zst', ref_storage_args= {"compression": "zstd"}, remote_protocol='s3', remote_options={'anon':True})

I get the error:

Traceback (most recent call last):
  File "/home/peter/Documents/intake_test/test_local.py", line 3, in <module>
    fs = fsspec.filesystem("reference", fo='ERA5_2020_2022_multivar.json.zst',ref_storage_args={"compression": "zstd"})
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/registry.py", line 262, in filesystem
    return cls(**storage_options)
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/spec.py", line 76, in __call__
    obj = super().__call__(*args, **kwargs)
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/implementations/reference.py", line 140, in __init__
    with open(fo, "rb", **dic) as f:
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/core.py", line 467, in open
    return open_files(
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/core.py", line 312, in open_files
    [
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/core.py", line 313, in <listcomp>
    OpenFile(
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/core.py", line 74, in __init__
    self.compression = get_compression(path, compression)
  File "/home/peter/anaconda3/envs/open_intake_min/lib/python3.10/site-packages/fsspec/core.py", line 513, in get_compression
    raise ValueError("Compression type %s not supported" % compression)
ValueError: Compression type zstd not supported

This occurs in a clean environment with the latest fsspec and s3fs installed. Running pip install zstandard fixes the error.

Reproduce the failure in a clean environment using the Reference Filesystem example and inspect fsspec/core.py together with fsspec/implementations/reference.py, the locations shown in the traceback. Check how the zstd compression option is resolved and how the optional zstandard dependency is handled. Done means the reported zstd workflow behaves as intended or its dependency requirement is explicitly covered by the project.