How to check if user exists with email (Firebase +) - SOLVED

const functions = require('firebase-functions');
const admin = require('firebase-admin');
exports.checkEmailExists = functions.https.onCall(async (data, context) => {
  const email = data.email;

  // 1. Validate Input
  if (!email || typeof email !== 'string') {
    throw new functions.https.HttpsError(
      'invalid-argument',
      'The function must be called with a valid email string.'
    );
  }

  try {
    // 2. Use Firebase Admin SDK to check if user exists by email
    // This will throw an error if the user does NOT exist.
    await admin.auth().getUserByEmail(email); // We don't need the userRecord object here, just if it succeeds or fails

    // If we reach here, it means getUserByEmail succeeded, so the user exists
    return { exists: true }; // Just return the boolean status

  } catch (error) {
    // 3. Handle specific 'auth/user-not-found' error
    if (error.code === 'auth/user-not-found') {
      return { exists: false }; // User does not exist
    }

    // 4. Re-throw other unexpected errors
    console.error("Error in checkEmailExists Cloud Function:", error);
    throw new functions.https.HttpsError(
      'unknown',
      'An unexpected error occurred while checking email existence.',
      error.message
    );
  }
});