fix

Author: RemDelaporteMathurin

src/festim/hydrogen_transport_problem.py

@@ -1882,7 +1882,8 @@ def run(self):
     def __del__(self):
         for export in self.exports:
             if isinstance(export, exports.ExportBaseClass):
-                export.writer.close()
+                if hasattr(export, "writer") and export.writer is not None:
+                    export.writer.close()
 
 
 class HydrogenTransportProblemDiscontinuousChangeVar(HydrogenTransportProblem):