Mark some Topic API properties as nonnull

voted, bookmarked, and ignored cannot be None.
see TopicQuery._process_result() in tildes/models/topic/topic_query.py

tildes/openapi_beta.yaml

@@ -316,13 +316,10 @@ components:
           nullable: true
         voted:
           type: boolean
-          nullable: true
         bookmarked:
           type: boolean
-          nullable: true
         ignored:
           type: boolean
-          nullable: true
         official:
           type: boolean
         tags:

tildes/tildes/models/topic/topic_query.py

@@ -142,7 +142,7 @@ class TopicQuery(PaginatedQuery):
             topic.bookmark_created_time = None
             topic.last_visit_time = None
             topic.comments_since_last_visit = None
-            topic.user_bookmarked = None
+            topic.user_bookmarked = False
             topic.user_ignored = False
         else:
             topic = result.Topic