The forum-topic skill-binding lookup assumed config.extra['group_topics']
was always a list of {chat_id, topics} entries. When an operator writes the
natural mapping shape ({"-100...": [...]}), iterating yields string keys and
chat_entry.get(...) raises AttributeError, breaking dispatch for that group.
Normalize both shapes to a common iterator and guard non-dict/non-list
entries so malformed config falls through cleanly instead of crashing.
5505dbbf43