Since e25295422 the subscriber loops in the comment, assigned, deleted and
project-created listeners logged a failed Notify and moved on. On SQLite the
insert regularly fails with "database is locked" (SQLITE_BUSY_SNAPSHOT: the
listener's deferred transaction cannot upgrade to a write once a sibling
listener has committed), so the notification was silently lost.
Return the error again so the events router retries the handler with a fresh
session, as it did before 2.5.0.
Reported at https://community.vikunja.io/t/notification-problems-since-2-5-0/4750
kolaente
536d7b7dbf