Fixed a bug that caused a crash when having empty technique ID entries within the 'exception' list of a data source administration YAML file.

data_source_mapping.py

@@ -189,7 +189,7 @@ def _load_data_sources(file, filter_empty_scores=True):
 
     name = yaml_content['name']
     platform = yaml_content['platform']
-    exceptions = [t['technique_id'] for t in yaml_content['exceptions']]
+    exceptions = [t['technique_id'] for t in yaml_content['exceptions'] if t['technique_id'] is not None]
 
     return my_data_sources, name, platform, exceptions