Hello, I want to make just one login page (no sign up page) and I want to make a default user inserted to db when someone uses my nextjs project that meant to run locally (npm run dev) so I want to prevent signup new accounts but also keep one default account only, how to do that in better auth ? I uses better-sqlite3, I test making a function that runs inside lib/auth.js automatically but return invalid query parameters even though I take the same code as inside the documentation, if anyone can help me thanks