2.4.0

Changed: the events listing shows an empty state instead of HTTP 500 when its tables are missing

The addon can be installed without its migrations having run — composer pulls the package in, the
nav item appears, and events and event_occurrences still do not exist. The listing asks both
tables a question while the page is being built (it counts each event's dates with
withCount('occurrences')), so the visitor got HTTP 500 and a stack trace for what is really an
unfinished setup. The listing now checks before its first query and renders a setup screen that
names the missing tables and says to run php artisan migrate.

The reason does not vanish with the 500: the guarded page writes to the log why it turned somebody
away. Otherwise the site would look installed and never work.