The validation added with the admin user checks reached further than intended.
The seed runs on every container start, not only on the first, and it threw on
three conditions that are normal on a second start.
The worst was the check for an existing user: after the first start the
default admin exists by definition, so every restart after that ended in a
container that would not come up. The insert is wrapped in a try and falls
back to an update precisely because it is meant to run again, and that path
was never reached.
The other two were narrower but the same shape. `validator.isEmail` rejects
`admin@localhost`, which is a common value in self-hosted setups, so an
instance that had been running for a year would stop coming up after the
upgrade.
None of it throws now. Bad input is reported on stderr and skipped, the way
an invalid username already was, and a username that belongs to someone else
is left alone rather than taken. `db:create-admin-user` keeps the strict
validation, which is where a person is there to read it and type again.
Daniel Hiller