add more checks for the date selection

[rkmd0]

e.g. add a warning if the date is in the past or the user selected sunday as a starting date (since for internationals the sunday regulation is unusual)
i was thinking about something like this but i think i would prefer having a yellow box for warnings, if possible:

  const selectedDate = new Date(document.getElementById("date").value);
  const today = new Date();

  if (selectedDate<today) {
    const toastTrigger = document.getElementById('startRouting');
    const toastLiveExample = document.getElementById('liveToast');

    if (toastTrigger) {
      const toastBootstrap = bootstrap.Toast.getOrCreateInstance(toastLiveExample);
      const errmsg = document.getElementById('errmsg');
      errmsg.textContent = "You cant select a day thats in the past";
      toastBootstrap.show();
    }
    return -1;
  }