Improved get_variables utils function

src/nomad_simulations/utils/utils.py

@@ -133,7 +133,7 @@ def is_not_representative(model_system, logger: BoundLogger):
 
 # cannot define typing with `Variables` due to circular import issue
 def get_variables(
-    variables: Optional[List[ArchiveSection]], variable_cls: ArchiveSection
+    variables: List[ArchiveSection], variable_cls: ArchiveSection
 ) -> List[ArchiveSection]:
     """
     Get the list of variables which are of type `variable_cls` and appear under `variables`.
@@ -145,8 +145,6 @@ def get_variables(
     Returns:
         (List[Variables]): The list of variables which are of type `variable_cls`.
     """
-    if variables is None:
-        return []
     result = []
     for var in variables:
         if isinstance(var, variable_cls):