Configuration for withPostgresClient.
Defaults to `getEnv('SUPABASE_DB_URL')` (from `@supabase/middleware`).
Pool size and checkout timeout for this connection string. Checked when the middleware is built; an invalid value throws a `RangeError` then. Entries whose options resolve to the same values share one pool.
How much of an error to include in a short-circuit response body.