Root cause of Tanko not responding to DMs after initial connection:
Zulip event queues expire after ~10min of dont_block polling. When the
queue expired, _api_call() returned None for all 400-level errors, which
_fetch_events() treated as 'no events' and returned []. The poll loop
never knew the queue died, so it never reconnected.
Fix:
1. _api_call() now returns (Optional[Dict], status_code) tuple
2. _fetch_events() explicitly checks for 400 status and raises
RuntimeError('BAD_EVENT_QUEUE_ID') for the poll loop to catch
3. All callers updated to unpack the tuple
Now when a queue expires, the poll loop catches the error and
calls _reconnect() to register a fresh queue.
Abiba (pi)
dcf2de0052