Bug Report: emailHarmony plugin causes error with missing normalized_email field

Describe the bug

When adding the emailHarmony() plugin to the plugins array, the application fails. The error occurs during user creation even though the database schema includes the normalized_email column and it's properly mapped in the configuration.

To Reproduce

1. Set up a project with better-auth and a SQLite database (in my case D1)
2. Create database migrations that include the normalized_email field on the users table
3. Configure better-auth with proper field mappings including normalizedEmail: "normalized_email"
4. Add the emailHarmony() plugin to the plugins array
5. Attempt to register/create a user
6. Observe the error

Expected behavior

The application should successfully create users with the normalized email populated by the emailHarmony plugin.

Code Example

// Auth client configuration
const auth = betterAuth({
  database: /* database connection */,
  user: {
    modelName: "users_table",
    fields: {
      // This mapping exists but seems to be ignored
      normalizedEmail: "normalized_email",
      // Other field mappings...
    },
  },
  // Other config...
  plugins: [
    emailHarmony(), // Adding this plugin causes the error
    // Other plugins...
  ],
});

Database schema

-- Users table with normalized_email column
CREATE TABLE users_table (
  id TEXT PRIMARY KEY,
  email TEXT UNIQUE,
  normalized_email TEXT,
  -- Other columns...
);

-- Unique index on normalized_email
CREATE UNIQUE INDEX idx_users_normalized_email ON users_table(normalized_email);

Error Details

The error appears to be related to database operations when the emailHarmony plugin is active. Execution fails during the user creation process in the Kysely query builder execution:

at async InsertQueryBuilder.execute (file:///node_modules/kysely/dist/esm/query-builder/insert-query-builder.js:916:24)
at async InsertQueryBuilder.executeTakeFirst (file:///node_modules/kysely/dist/esm/query-builder/insert-query-builder.js:934:26)
at async withReturning (file:///node_modules/better-auth/dist/shared/better-auth.HHZU10im.mjs:254:13)
at async Object.create (file:///node_modules/better-auth/dist/shared/better-auth.HHZU10im.mjs:277:9)

Environment

• better-auth: ^1.2.3
• better-auth-harmony: ^1.2.3
• kysely-d1: ^0.3.0
• Node.js: (v23.7.0
• Database: SQLite (D1)

Additional context

I've verified that:

1. The database schema contains the normalized_email column
2. The field is correctly mapped in the configuration
3. Everything works until the emailHarmony() plugin is added