more bug fixes for missing data

algo.py

@@ -188,8 +188,10 @@ class Algo:
                 heterogeneous_exists = True
                 break
             else:
-                if most_conservative_mapping is None or mapping['dry_matter_content'] < most_conservative_mapping['dry_matter_content']:
-                    most_conservative_mapping = mapping
+                dry_matter_content = mapping.get('dry_matter_content')
+                if dry_matter_content is not None:
+                    if most_conservative_mapping is None or dry_matter_content < most_conservative_mapping['dry_matter_content']:
+                        most_conservative_mapping = mapping
 
         mixture_data = {}
         if heterogeneous_exists: