Map is_shown_by even if record has no type

metadata_mapper/mappers/oai/content_dm/contentdm_mapper.py

@@ -31,13 +31,11 @@ def map_is_shown_by(self):
         To run post mapping. For this one, is_shown_by needs sourceResource/type
         """
         record_type = self.map_type()
-        if not record_type:
-            return
-
-        record_types = [record_type] if isinstance(record_type, str) else record_type
 
-        if "sound" in [t.lower() for t in record_types]:
-            return None
+        if record_type:
+            record_types = [record_type] if isinstance(record_type, str) else record_type
+            if "sound" in [t.lower() for t in record_types]:
+                return None
 
         return self.get_preview_image_url()
 
@@ -71,6 +69,7 @@ def get_preview_image_url(self):
         feed's object_id, but larger images are sometimes available.
         """
         larger_preview_image = self.get_larger_preview_image_url()
+
         if larger_preview_image:
             return larger_preview_image