Fix the check for is_key_optional.

(cherry picked from commit da260a9742d5060804ece46001f85a74f44a70a1)

cl/runtime/db/local/local_cache.py

@@ -55,8 +55,11 @@ def load_one(
         is_record_optional: bool = False,
     ) -> TRecord | None:
         # Check for an empty key
-        if not is_key_optional and record_or_key is None:
-            raise UserError(f"Key is None when trying to load record type {record_type.__name__} from DB.")
+        if record_or_key is None:
+            if is_key_optional:
+                return None
+            else:
+                raise UserError(f"Key is None when trying to load record type {record_type.__name__} from DB.")
 
         if record_or_key is None or getattr(record_or_key, "get_key", None) is not None:
             # Key instance is Record or None, return without lookup

cl/runtime/db/mongo/basic_mongo_db.py

@@ -70,8 +70,11 @@ def load_one(
         is_record_optional: bool = False,
     ) -> TRecord | None:
         # Check for an empty key
-        if not is_key_optional and record_or_key is None:
-            raise UserError(f"Key is None when trying to load record type {record_type.__name__} from DB.")
+        if record_or_key is None:
+            if is_key_optional:
+                return None
+            else:
+                raise UserError(f"Key is None when trying to load record type {record_type.__name__} from DB.")
 
         if record_or_key is None or getattr(record_or_key, "get_key", None) is not None:
             # Record or None, return without lookup

cl/runtime/db/sql/sqlite_db.py

@@ -104,8 +104,11 @@ def load_one(
         is_record_optional: bool = False,
     ) -> TRecord | None:
         # Check for an empty key
-        if not is_key_optional and record_or_key is None:
-            raise UserError(f"Key is None when trying to load record type {record_type.__name__} from DB.")
+        if record_or_key is None:
+            if is_key_optional:
+                return None
+            else:
+                raise UserError(f"Key is None when trying to load record type {record_type.__name__} from DB.")
 
         # Delegate to load_many
         result = next(iter(self.load_many(record_type, [record_or_key], dataset=dataset, identity=identity)))