Add a GroupNotFoundError

Author: dstansby

src/zarr/api/asynchronous.py

@@ -39,7 +39,7 @@
 )
 from zarr.core.metadata import ArrayMetadataDict, ArrayV2Metadata, ArrayV3Metadata
 from zarr.core.metadata.v2 import _default_compressor, _default_filters
-from zarr.errors import NodeTypeValidationError
+from zarr.errors import GroupNotFoundError, NodeTypeValidationError
 from zarr.storage._common import make_store_path
 
 if TYPE_CHECKING:
@@ -837,7 +837,7 @@ async def open_group(
             overwrite=overwrite,
             attributes=attributes,
         )
-    raise FileNotFoundError(f"Unable to find group: {store_path}")
+    raise GroupNotFoundError(store, store_path.path)
 
 
 async def create(

src/zarr/errors.py

@@ -10,7 +10,7 @@
 ]
 
 
-class BaseZarrError(ValueError):
+class BaseZarrError(Exception):
     """
     Base error which all zarr errors are sub-classed from.
     """
@@ -21,6 +21,14 @@ def __init__(self, *args: Any) -> None:
         super().__init__(self._msg.format(*args))
 
 
+class GroupNotFoundError(BaseZarrError, FileNotFoundError):
+    """
+    Raised when a group isn't found at a certain path.
+    """
+
+    _msg = "No group found in store {!r} at path {!r}"
+
+
 class ContainsGroupError(BaseZarrError):
     """Raised when a group already exists at a certain path."""