add null guard in create user use case

app/User/UseCases/CreateUser.php

@@ -2,6 +2,7 @@
 
 namespace App\User\UseCases;
 
+use App\Exceptions\BadRequestException;
 use App\User\UserRepository;
 use App\ValueObjects\EmailAddress;
 
@@ -13,6 +14,10 @@ class CreateUser
 
     public function execute(CreateUserRequest $dto): void
     {
+        if ($dto->email === null) {
+            throw new BadRequestException('email is required');
+        }
+
         $this->userRepo->create(new CreateUserDto(
             email: new EmailAddress($dto->email),
         ));