Don't show broken image previews when cover is absent

bookwyrm/connectors/self_connector.py

@@ -69,6 +69,10 @@ class Connector(AbstractConnector):
         return search_results
 
     def format_search_result(self, search_result):
+        cover = None
+        if search_result.cover:
+            cover = "%s%s" % (self.covers_url, search_result.cover)
+
         return SearchResult(
             title=search_result.title,
             key=search_result.remote_id,
@@ -77,7 +81,7 @@ class Connector(AbstractConnector):
             if search_result.published_date
             else None,
             connector=self,
-            cover="%s%s" % (self.covers_url, search_result.cover),
+            cover=cover,
             confidence=search_result.rank if hasattr(search_result, "rank") else 1,
         )