Fix bug: Retrieval of dbxrefs without registered retrievers causes an exception

dbxref/retriever.py

@@ -12,6 +12,7 @@ def retrieve(dbxrefs):
         if config.has_provider(key):
             provider = config.get_provider(key)
             logger.debug('{0} is supported'.format(key))
+            if 'retriever' in provider:
               if provider['retriever']['type'] == 'external':
                   results.extend( load_with_external_provider(provider, list(dbxrefs)))
               elif provider['retriever']['type'] == 'internal':
@@ -19,8 +20,11 @@ def retrieve(dbxrefs):
               else:
                   raise Exception('Unknown retriever type', provider['retriever']['type'])
             else:
-            logger.debug('{0} is not supported'.format(key))
-            results.extend( map(lambda x: {'id': toString(x), 'status': 'not supported'}, dbxrefs))
+              logger.debug('Retrieval of {0} is not supported'.format(key))
+              results.extend( map(lambda x: {'id': toString(x), 'status': 'retrieval not supported'}, dbxrefs))
+        else:
+            logger.debug('Retrieval of {0} is not supported'.format(key))
+            results.extend( map(lambda x: {'id': toString(x), 'status': 'retrieval not supported'}, dbxrefs))
     return (results)
 
 def load_with_external_provider(provider, dbxrefs):