fix: lints

src/pystac/item.py

@@ -117,8 +117,14 @@ def set_collection(self, collection: Collection | None) -> None:
             self.remove_links(COLLECTION)
 
     def get_collection(self) -> Collection | None:
+        from .collection import Collection
+
         if link := self.get_link(COLLECTION):
-            return link.get_stac_object()
+            stac_object = link.get_stac_object()
+            if isinstance(stac_object, Collection):
+                return stac_object
+            else:
+                return None
         else:
             return None
 
@@ -154,7 +160,7 @@ def _to_dict(self) -> dict[str, Any]:
         return d
 
 
-def _parse_datetime(value: str | dt.datetime | None) -> dt.datetime:
+def _parse_datetime(value: str | dt.datetime | None) -> dt.datetime | None:
     if value is None or isinstance(value, dt.datetime):
         return value
     else:

src/pystac/stac_object.py

@@ -330,7 +330,7 @@ def set_self_link(self) -> None:
             self.set_link(Link.self(self))
 
     @deprecate.function("Prefer to get the href directly")
-    def get_self_href(self) -> str:
+    def get_self_href(self) -> str | None:
         return self.href
 
     @deprecate.function("Prefer to set href directly, and then use `render()`")

src/pystac/utils.py

@@ -253,7 +253,7 @@ def datetime_to_str(dt: datetime.datetime, timespec: str = "auto") -> str:
     return timestamp
 
 
-def str_to_datetime(s: str) -> datetime:
+def str_to_datetime(s: str) -> datetime.datetime:
     return dateutil.parser.isoparse(s)