`bin/migrateDB.ts` opens a source and target ueberdb2 Database, copies all
keys, then resolves without closing either connection or calling
process.exit(). Two problems with ueberdb2 6.1.x:
- 6.1.x keeps an internal keep-alive timer running until close() is called,
so the migration process hangs forever after "Done syncing dbs" instead
of exiting. (Pre-6.1.x it exited on its own once the work was done.)
- Target writes are buffered and only guaranteed flushed to disk on close()
/flush(), so an operator who Ctrl-Cs the apparently-finished process could
end up with an incomplete migration.
Close the target then the source on both the success and error paths (which
flushes buffered writes and clears the keep-alive timer) and exit with an
explicit status code, matching the pattern already used in
migrateDirtyDBtoRealDB.ts.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
