[Answer]-Django other_dict Error

you should default return (fallback dict) when the boolean expression is not satisfied, something like:

if request.user.is_authenticated():
    ...
    return {
        'notification_events': events,
        'notification_mails': mails
    }
else:
    #fallback
    return {
        'notification_events': None,
        'notification_mails': None
    }