Additional Fields Issue In Database Hooks

// Schema definition has fields
const user = pgTable("user", {
  firstName: text("first_name"),
  lastName: text("last_name"),
  // ...other fields
});

// Auth config includes them
const auth = betterAuth({
  database: drizzleAdapter(db, {
    schema: { user }  // User table with firstName/lastName
  }),
  user: {
    additionalFields: {
      firstName: {
        type: "string",
        fieldName: "firstName",
      },
      lastName: {
        type: "string",
        fieldName: "lastName",
      }
    }
  }
});

databaseHooks: {
  user: {
    create: {
      after: async (user) => {
        // TypeScript complains about firstName not existing
        // but running this shows firstName is actually there:
        console.log('Full user object:', user); // {id: '123', firstName: 'John', ...}
        
        // Need type assertion even though data exists at runtime
        const extendedUser = user as { firstName: string };
        console.log(extendedUser.firstName); // Works and shows 'John'
        
        // Direct access gives TS error even though it works
        console.log(user.firstName); --> TY Error
        // TS Error: Property 'firstName' does not exist on type '{ id: string; email: string; emailVerified: boolean; name: string; createdAt: Date; updatedAt: Date; image?: string | null | undefined; }'
      }
    }
  }
}