i think this fixes the room pagination limit.

rather than aborting on the final partial pagination, it instead paginates the remainder, and then aborts if you try to go any further.

synapse/handlers/room_list.py

@@ -238,9 +238,12 @@ class RoomListHandler(BaseHandler):
                 addition *= -1
 
             try:
-                new_limit = sorted_rooms.index(last_room_id) + addition
-                if new_limit >= len(sorted_rooms):
+                if sorted_rooms.index(last_room_id) == len(sorted_rooms):
                     new_limit = None
+                else:
+                    new_limit = sorted_rooms.index(last_room_id) + addition
+                    if new_limit >= len(sorted_rooms):
+                        new_limit = len(sorted_rooms)
             except ValueError:
                 pass