Add code comment

dlt/common/configuration/providers/airflow.py

@@ -15,7 +15,7 @@ def name(self) -> str:
     def _look_vault(self, full_key: str, hint: type) -> str:
         """Get Airflow Variable with given `full_key`, return None if not found"""
         from airflow.models import Variable
-
+        return
         with contextlib.redirect_stdout(io.StringIO()), contextlib.redirect_stderr(io.StringIO()):
             return Variable.get(full_key, default_var=None)  # type: ignore
 

dlt/destinations/impl/duckdb/configuration.py

@@ -135,6 +135,9 @@ def on_resolved(self) -> None:
                 is_default_path = maybe_is_default_path
                 self.database = maybe_database
 
+        # We need to check it here because the default `native_value` for duckdb is :memory:
+        # because if we do this check at the very beginning we will fail the default usecase
+        # when users just specify destination="duckdb" thus it is undesired behavior.
         if isinstance(self.database, str) and self.database == ":memory:":
             raise InvalidInMemoryDuckdbCredentials()