G.sentry_event_id is not set in time

I was wondering how g.sentry_event_id in Flask/Python tends to be used. Relevant docs: https://docs.sentry.io/clients/python/integrations/flask/#getting-the-last-event-id

In my case, I’m using the Flask/Raven integration to set up sentry (sentry.init_app(...)) - this sets up recording of g.sentry_event_id using Flask’s got_request_exception. When I register a Flask blueprint’s errorhandler, g.sentry_event_id is not set yet, presumably because it’s being called before Raven code is hit.

Does this mean the only way for this to work is if I explicitly call sentry.captureException in 1st-party code? Is it expected that the approach I outlined above wouldn’t work?