chore: change the email creation dto

src/modules/users/entities/user.entity.ts

@@ -48,8 +48,8 @@ export class User extends BaseEntity {
   @ManyToOne(() => Business, { deleteRule: "restrict" })
   business!: Business;
 
-  @ManyToOne(() => Domain, { nullable: true })
-  domain?: Domain; // The domain this email user belongs to
+  @ManyToOne(() => Domain, { deleteRule: "restrict" })
+  domain!: Domain; // The domain this email user belongs to
 
   [EntityRepositoryType]?: UserRepository;
 }