Handle release manager schedule not existing
When a schedule definition doesn't exist for the current version, we were previously returning an empty array, which our API apparently treats as a bad request, causing a 400 in the client, causing an exception in release-tools.
We now raise VersionNotFoundError
, and rescue that in MonthlyIssue
in order to return nil
, which the API likes just fine. Consistency!
See https://sentry.gitlab.net/gitlab/release-tools/issues/662264/
Closes https://gitlab.com/gitlab-org/release/framework/issues/228