issues: 1203835220

What happened?

Currently if someone supplies a path that doesn't exist, we get quite a long stack trace, without really saying that the path doesn't exist.

What did you expect to happen?

Possibly a FileNotFoundError

Minimal Complete Verifiable Example

Python xr.open_zarr('x.zarr')

Relevant log output

```Python In [1]: xr.open_zarr('x.zarr') <ipython-input-1-8be4b98d9b20>:1: RuntimeWarning: Failed to open Zarr store with consolidated metadata, falling back to try reading non-consolidated metadata. This is typically much slower for opening a dataset. To silence this warning, consider:

1. Consolidating metadata in this existing store with zarr.consolidate_metadata().
2. Explicitly setting consolidated=False, to avoid trying to read consolidate metadata, or
3. Explicitly setting consolidated=True, to raise an error in this case instead of falling back to try reading non-consolidated metadata. xr.open_zarr('x.zarr')

---

KeyError Traceback (most recent call last) ~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/xarray/backends/zarr.py in open_group(cls, store, mode, synchronizer, group, consolidated, consolidate_on_close, chunk_store, storage_options, append_dim, write_region, safe_chunks, stacklevel) 347 try: --> 348 zarr_group = zarr.open_consolidated(store, **open_kwargs) 349 except KeyError:

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/zarr/convenience.py in open_consolidated(store, metadata_key, mode, **kwargs) 1186 # setup metadata store -> 1187 meta_store = ConsolidatedMetadataStore(store, metadata_key=metadata_key) 1188

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/zarr/storage.py in init(self, store, metadata_key) 2643 # retrieve consolidated metadata -> 2644 meta = json_loads(store[metadata_key]) 2645

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/zarr/storage.py in getitem(self, key) 894 else: --> 895 raise KeyError(key) 896

KeyError: '.zmetadata'

During handling of the above exception, another exception occurred:

GroupNotFoundError Traceback (most recent call last) <ipython-input-1-8be4b98d9b20> in <cell line: 1>() ----> 1 xr.open_zarr('x.zarr')

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/xarray/backends/zarr.py in open_zarr(store, group, synchronizer, chunks, decode_cf, mask_and_scale, decode_times, concat_characters, decode_coords, drop_variables, consolidated, overwrite_encoded_chunks, chunk_store, storage_options, decode_timedelta, use_cftime, **kwargs) 750 } 751 --> 752 ds = open_dataset( 753 filename_or_obj=store, 754 group=group,

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/xarray/backends/api.py in open_dataset(filename_or_obj, engine, chunks, cache, decode_cf, mask_and_scale, decode_times, decode_timedelta, use_cftime, concat_characters, decode_coords, drop_variables, backend_kwargs, args, *kwargs) 493 494 overwrite_encoded_chunks = kwargs.pop("overwrite_encoded_chunks", None) --> 495 backend_ds = backend.open_dataset( 496 filename_or_obj, 497 drop_variables=drop_variables,

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/xarray/backends/zarr.py in open_dataset(self, filename_or_obj, mask_and_scale, decode_times, concat_characters, decode_coords, drop_variables, use_cftime, decode_timedelta, group, mode, synchronizer, consolidated, chunk_store, storage_options, stacklevel) 798 799 filename_or_obj = _normalize_path(filename_or_obj) --> 800 store = ZarrStore.open_group( 801 filename_or_obj, 802 group=group,

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/xarray/backends/zarr.py in open_group(cls, store, mode, synchronizer, group, consolidated, consolidate_on_close, chunk_store, storage_options, append_dim, write_region, safe_chunks, stacklevel) 363 stacklevel=stacklevel, 364 ) --> 365 zarr_group = zarr.open_group(store, **open_kwargs) 366 elif consolidated: 367 # TODO: an option to pass the metadata_key keyword

~/Library/Caches/pypoetry/virtualenvs/-x204KUJE-py3.9/lib/python3.9/site-packages/zarr/hierarchy.py in open_group(store, mode, cache_attrs, synchronizer, path, chunk_store, storage_options) 1180 if contains_array(store, path=path): 1181 raise ContainsArrayError(path) -> 1182 raise GroupNotFoundError(path) 1183 1184 elif mode == 'w':

GroupNotFoundError: group not found at path '' ```

Anything else we need to know?

No response

Environment

INSTALLED VERSIONS

commit: None python: 3.9.12 (main, Mar 26 2022, 15:44:31) [Clang 13.1.6 (clang-1316.0.21.2)] python-bits: 64 OS: Darwin OS-release: 21.3.0 machine: arm64 processor: arm byteorder: little LC_ALL: en_US.UTF-8 LANG: None LOCALE: ('en_US', 'UTF-8') libhdf5: None libnetcdf: None

xarray: 2022.3.0 pandas: 1.4.1 numpy: 1.22.3 scipy: None netCDF4: None pydap: None h5netcdf: None h5py: None Nio: None zarr: 2.11.1 cftime: None nc_time_axis: None PseudoNetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: 2021.12.0 distributed: 2021.12.0 matplotlib: None cartopy: None seaborn: None numbagg: None fsspec: 2021.11.1 cupy: None pint: None sparse: None setuptools: 60.9.3 pip: 21.3.1 conda: None pytest: 6.2.5 IPython: 7.32.0 sphinx: None