sealed interface TypeError  {
    val error: String
    class WrongName(override val error: String) : TypeError
}

@Serializable
@JvmInline
value class Surname private constructor(
  val name: String) {
  companion object {
    private val rightRegister = Regex("\\p{Lu}\\p{Ll}+")
    operator fun invoke(name: String): 
      Either<TypeError, Surname> = either {
        ensure(rightRegister.matches(name)) { 
          TypeError.WrongName("Wrong Surname") }
        Surname(name) } }
  override fun toString() = name }

operator fun invoke(
  firstname: Either<TypeError, Firstname>,
  surname: Either<TypeError, Surname>
): EitherNel<TypeError, Student> = either {
  zipOrAccumulate(
    { firstname.bind() },
    { surname.bind() },
    { if (firstname.getOrNull()?.name == 
      surname.getOrNull()?.name)
      raise(TypeError.WrongName("Firstname = Surname")) }
  ) { f, s, _ -> Student(f, s) }
}

onClick = {
  val student: Either<NonEmptyList<TypeError>, Student> = 
    Student(Firstname(firstname), Surname(surname))
  labelRef.current?.textContent = when (student) {
    is Either.Left -> 
      student.value.joinToString { it.error }
    is Either.Right -> {
      props.saveElement(student.value)
      "" }
  }
}