Fix type errors where metadata could be None.

Author: jaraco

importlib_metadata/__init__.py

@@ -543,7 +543,7 @@ def _assemble_message(text: str) -> _meta.PackageMetadata:
     @property
     def name(self) -> str:
         """Return the 'Name' metadata for the distribution package."""
-        return self.metadata['Name']
+        return cast(PackageMetadata, self.metadata)['Name']
 
     @property
     def _normalized_name(self):
@@ -553,7 +553,7 @@ def _normalized_name(self):
     @property
     def version(self) -> str:
         """Return the 'Version' metadata for the distribution package."""
-        return self.metadata['Version']
+        return cast(PackageMetadata, self.metadata)['Version']
 
     @property
     def entry_points(self) -> EntryPoints:
@@ -1050,7 +1050,7 @@ def distributions(**kwargs) -> Iterable[Distribution]:
     return Distribution.discover(**kwargs)
 
 
-def metadata(distribution_name: str) -> _meta.PackageMetadata:
+def metadata(distribution_name: str) -> _meta.PackageMetadata | None:
     """Get the metadata for the named package.
 
     :param distribution_name: The name of the distribution package to query.
@@ -1125,7 +1125,7 @@ def packages_distributions() -> Mapping[str, list[str]]:
     pkg_to_dist = collections.defaultdict(list)
     for dist in distributions():
         for pkg in _top_level_declared(dist) or _top_level_inferred(dist):
-            pkg_to_dist[pkg].append(dist.metadata['Name'])
+            pkg_to_dist[pkg].append(cast(PackageMetadata, dist.metadata)['Name'])
     return dict(pkg_to_dist)
 
 

importlib_metadata/compat/py39.py

@@ -4,14 +4,16 @@
 
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, cast
 
 if TYPE_CHECKING:  # pragma: no cover
     # Prevent circular imports on runtime.
     from .. import Distribution, EntryPoint
 else:
     Distribution = EntryPoint = Any
 
+from .._meta import PackageMetadata
+
 
 def normalized_name(dist: Distribution) -> str | None:
     """
@@ -22,7 +24,9 @@ def normalized_name(dist: Distribution) -> str | None:
     except AttributeError:
         from .. import Prepared  # -> delay to prevent circular imports.
 
-        return Prepared.normalize(getattr(dist, "name", None) or dist.metadata['Name'])
+        return Prepared.normalize(
+            getattr(dist, "name", None) or cast(PackageMetadata, dist.metadata)['Name']
+        )
 
 
 def ep_matches(ep: EntryPoint, **params) -> bool: