fix: UI validation for existing email during user registration

.changeset/open-toes-vanish.md

@@ -0,0 +1,6 @@
+---
+'@rocket.chat/meteor': patch
+'@rocket.chat/web-ui-registration': patch
+---
+
+Fixes email validation in the registration form to prevent users from registering with an already existing email address.

apps/meteor/app/api/server/v1/users.ts

@@ -36,6 +36,7 @@ import { sendConfirmationEmail } from '../../../../server/methods/sendConfirmati
 import { getUserForCheck, emailCheck } from '../../../2fa/server/code';
 import { resetTOTP } from '../../../2fa/server/functions/resetTOTP';
 import { hasPermissionAsync } from '../../../authorization/server/functions/hasPermission';
+import { checkEmailAvailability } from '../../../lib/server/functions/checkEmailAvailability';
 import {
 	checkUsernameAvailability,
 	checkUsernameAvailabilityWithValidation,
@@ -649,7 +650,9 @@ API.v1.addRoute(
 			if (!(await checkUsernameAvailability(this.bodyParams.username))) {
 				return API.v1.failure('Username is already in use');
 			}
-
+			if (!(await checkEmailAvailability(this.bodyParams.email))) {
+				return API.v1.failure('Email is already in use');
+			}
 			if (this.bodyParams.customFields) {
 				try {
 					await validateCustomFields(this.bodyParams.customFields);

packages/web-ui-registration/src/RegisterForm.tsx

@@ -93,7 +93,7 @@ export const RegisterForm = ({ setLoginRoute }: { setLoginRoute: DispatchLoginRo
 					if (error.errorType === 'error-user-already-exists') {
 						setError('username', { type: 'user-already-exists', message: t('registration.component.form.usernameAlreadyExists') });
 					}
-					if (/Email already exists/.test(error.error)) {
+					if (/Email is already in use/.test(error.error)) {
 						setError('email', { type: 'email-already-exists', message: t('registration.component.form.emailAlreadyExists') });
 					}
 					if (/Username is already in use/.test(error.error)) {