fixes for cases where strain and sex attributes are empty

species_data.py

@@ -118,9 +118,10 @@ class SpeciesData:
         self.full_name = ' '.join(utilities.filter_empty_not_empty_items([self.genus_uppercase, self.species_lowercase, self.strain, self.sex])["not_empty"])
         self.full_name_lowercase = self.full_name.lower()
 
-        self.species_folder_name = "_".join(utilities.filter_empty_not_empty_items(
-            [self.genus_lowercase, self.species_lowercase, self.strain.lower(),
-             self.sex.lower()])["not_empty"])
+        self.species_folder_name = "_".join(utilities.filter_empty_not_empty_items([self.genus_lowercase,
+                                                                                    self.species_lowercase,
+                                                                                    self.strain_lowercase,
+                                                                                    self.sex_lowercase])["not_empty"])
 
         self.dataset_prefix = self.strain_sex